If you don't receive the email to confirm your email:
Check your spam filters
Try again on a different device or a different network
Try with a different email address.
Disposable email addresses are not accepted by Gamma, so if you signed up using a disposable email address, you will not receive a confirmation email. In this case, sign up using a standard domain such as gmail or icloud.
Also see: I can't log in to my Gamma account