Sign up for Claude and install Claude Code

Lesson outcome

You will have a Claude Pro or Max subscription and Claude Code installed and ready to run on your local machine.

Why this matters in an agency

Claude Code is the primary interface for this entire course and for the operator stack you are building. Without it installed, nothing else works. This lesson gets you from zero to a working installation as quickly as possible.

Inputs, tools, and prerequisites

A computer (Mac or Windows), a credit card for the Claude subscription, and a terminal (which you used in the previous module). You will also need to install Node.js, which is a prerequisite for Claude Code.

Step-by-step walkthrough

Sign up for Claude Pro or Max

Go to claude.ai and create an account if you do not already have one. After creating the account, subscribe to either the Pro plan ($20/month) or the Max plan ($100/month).

The Pro plan gives you generous usage for day-to-day work. The Max plan gives you significantly more usage and priority access. If you are not sure, start with Pro. You can upgrade later at any time.

Claude Code uses your Claude subscription directly. You do not need a separate API key. You do not need to set up billing through the Anthropic API console. When you sign into Claude Code, it authenticates against your existing Claude account and uses your plan's allocation. This is one of the simplest parts of the setup.

Install Node.js

Claude Code requires Node.js version 18 or higher. Node.js is a program that lets tools written in JavaScript run on your computer. You do not need to learn JavaScript. You just need Node.js installed so Claude Code can run.

Go to nodejs.org. The site will recommend a version for your operating system. Download the LTS (Long Term Support) version — that is the stable, recommended one.

On Mac, download the .pkg installer and run it. Follow the prompts with default settings.

On Windows, download the .msi installer and run it. Follow the prompts with default settings. Make sure the option to add Node.js to your PATH is checked (it usually is by default).

After installation, close your current terminal and open a new one. The new terminal will pick up the updated PATH so it can find Node.js. Verify the installation:

```
node --version
```

You should see something like v22.14.0 or a similar version number at or above 18. If you see "command not found," Node.js was not installed correctly or you did not open a new terminal.

Also verify npm (Node Package Manager), which comes bundled with Node.js:

```
npm --version
```

You should see a version number. npm is the tool you will use to install Claude Code in the next step.

Install Claude Code

In your terminal, run:

```
npm install -g @anthropic-ai/claude-code
```

The -g flag means "install globally" — this makes the claude command available from anywhere on your system, not just one folder.

On Mac, if you get a permissions error, prefix the command with sudo:

```
sudo npm install -g @anthropic-ai/claude-code
```

It will ask for your computer's login password (not your Bitwarden master password or your Claude password).

On Windows, if you get a permissions error, close PowerShell and reopen it as Administrator (right-click the PowerShell icon and select "Run as administrator"), then run the install command again.

The installation takes a minute or two. When it finishes, verify:

```
claude --version
```

You should see a version number. Claude Code is installed.

Sign in to Claude Code

Run Claude Code for the first time:

```
claude
```

Claude Code will open your web browser to a sign-in page. Sign in with the same account you used to subscribe to Claude Pro or Max.

After signing in, the browser will redirect back and Claude Code will be authenticated in your terminal. You should see a welcome message or a prompt. Claude Code is ready.

If the browser does not open automatically, Claude Code will display a URL for you to visit manually. Copy that URL, paste it into your browser, and complete the sign-in there.

Failure modes and verification checks

The most common failures are: Node.js not being found (close and reopen your terminal after installing), npm permission errors (use sudo on Mac or run as Administrator on Windows), and browser authentication not completing (try the manual URL method if the browser did not open automatically).

Verification: run claude --version and confirm it prints a version number. Then run claude and confirm it starts without errors.

Implementation checklist

• Subscribe to Claude Pro or Max at claude.ai.
• Download and install Node.js LTS from nodejs.org.
• Verify Node.js with node --version.
• Install Claude Code with npm install -g @anthropic-ai/claude-code.
• Verify Claude Code with claude --version.
• Run claude and complete the browser authentication.

Immediate next action

Leave Claude Code running and move to the next lesson. You are about to have your first conversation.

Exercise

Run node --version, npm --version, and claude --version in your terminal and write down all three version numbers. This is your installation snapshot. If something breaks later, these numbers help diagnose what changed. Create a note in your Obsidian vault called "Stack Versions" and record them there. This is your first time using the vault for something real, even if it is small.