I found a bug which is weird.
When I set the “Default Role at Time of Signup” as a “Customer”, and user from the sign up created as a “Customer” role, it cannot save the address while checkout and cannot access the sales order due to a permission error here:
After that, I tried to change the “Default Role at Time of Signup” to a “Non-Profit Portal User” role and tried to create a user from Sign Up for the first time. Then I change this user role manually into the “Customer” Role from the Administrator, and it works:
I hope that the “Customer” Role after the set-up in the “Default Role at Time of Signup” bug can be fixed as soon as possible, thank you