I read a few topics/FAQs here, and noticed you need to sign with a crypto address which you had on your account.
The thing is, I've never posted a crypto address here nor have I got one linked on my account.
See here:
If you forgot the password or similarTry using the
email password reset. Check that the email isn't ending up in your spam folder. If that doesn't work, email
recoveries_2021_xxlgg@bitcointalk.org, ideally
from the account's email address. Include your
username. A signature will likely be required (see below).
Having a digital signature option is not a requirement, particularly when you have access to both email addresses as mentioned. Simply make sure to send an email to support from your old email address.