All accounts used to log into Red Giant (via redgiant.com) were transferred to the MyMaxon system in 2021.
Emails about the transfer process were sent out to all affected parties via whatever address they'd used for their redgiant.com account.
Users can now sign into my.maxon.net using the same email they'd used on redgiant.com.
The password was setup through a Reset Password process; just use the Forgot Password option if you did not receive that email, or if you'd like to change the password.
Once signed in, you can access your Red Giant serials through the Manage section, as well as update your email address if you need to.