Restricting user sign up with google sheets

Hello. We have finally launched our app and are seeing customers - :+1:

However, currently we don’t have a way to enforce users to use the email that they used when purchasing (for signing up).

How could this be achieved? I am thinking having a Google sheet, in which user emails get added after a purchase, and then adalo only lets emails from that list to sign up. When visiting for the first time, user is required to enter the same email he used when purchasing and has to create a password.

All solutions are welcome, could be custom integration as well.

Thank you!

Hello, users sign up restrictions can be done without Google sheets.

Thank you!

Do you have an article or a tutorial? Or could you briefly explain?

Thing is, the email will and must come from our checkout page (external). So we need to pass those emails to Adalo