I only have the CRA on my phone. I access it by using my fingerprint. I have no other way to access autofill on my desktop. Any ideas

If you are registered for CRA MyAccount, then you have a username & password, even if you use the biometric login option on your phone. This CRA page tells you how you can recover your username and/or password: https://www.canada.ca/en/revenue-agency/services/e-services/cra-login-services/help-cra-sign-in-services/cra-userid-password.html#section3b