I have an privaterelay.appleid.com email address that associated with Canva app that I pay for but I can't login to that email because I don't know where to login from and I don't know the password. Can you help me

Thanks for posting in the Apple Support Communities JustAdriGarcia,

The following information applies specifically to using Hide My Email, we think you'll find this helpful:

If you create an account with an app or visit a website that supports Sign in with Apple, you can choose to share your email address, if you're familiar with the app or website, or hide your email address, if you'd prefer more privacy. If you choose the Hide my Email option, only the app or website you created the account with can use this random email address to communicate with you. Learn more about Sign in with Apple. 

Messages sent to a private relay email address, are forwarded to your personal inbox.

At any time, you can change the email address that receives forwarded messages. Or you can choose to turn off email forwarding to stop receiving messages. You can manage your addresses created with Hide My Email in Settings on your iPhone, iPad, or iPod touch, or on iCloud.com.

Take care!