Go to classroom.google.com and click Go to Classroom. Enter the email address for your Classroom account and click Next. Enter your password and click Next. If there is a welcome message, review it and click Accept. If you're using an Google Workspace for Education account, click I’m A Student or I’m A Teacher.
Enter the Google Account email address and password, then click Next. Follow the steps that appear. Tip: If your friend doesn't have an account, they can create a Google Account. What info people will see. When someone signs in to your Chromebook, they’ll see all their data synced in Chrome, like apps, wallpaper, and bookmarks.
Sign in - Google Accounts