There are multiple ways in which people can accept their invites. They include email notifications, mobile and web notifications, and by using a link acquired via social media or other sharing methods.
SIGN UP BY EMAIL
1. Once you receive an invite from your group/course admin, you need to follow the invite link from the email
2. Fill out the sign-up form and click the Sign Up button
3. Confirm your email and join the group/course
Should you choose to sign up using your Google account, please follow the steps from this article: How do sign up/sign in with my Google account?