Google Services and Valid Google Accounts
There are basically three types of Google accounts:
Free Gmail account
G-Suite domain account
Drive-only account using a non-google account @ aol.com, msn.com, yahoo.com, comcast.net, wavecable.com, etc.
Type 1 is fairly obvious. Type 2 is like what a business or anyone with a custom domain name would use for multiple accounts within that domain. SkagitDemocrats.org is a Google Domain.
Over the years, many have unknowingly created the type 3 Google account. If you are one of those people, you can check by trying to use it to logon by visiting accounts.google.com. If it asks you for a password, you have a type 3 account. Otherwise it will complain that the account does not exist.