Can no longer log into Google mail because of security

I had to reset my Google account password, and now am no longer able to connect Mac Mail to my Gmail amount. I am getting this error message

Authorization Error

Error 400: invalid_request

You can't sign in to this app because it doesn't comply with Google's OAuth 2.0 policy for keeping apps secure.

You can let the app developer know that this app doesn't comply with one or more Google validation rules.

I've searched for a solution and found this, which I've done, but now still cannot connect to my Gmail account

Google still offers a workaround for applications that don't use OAuth2, but they don't publicize it. You need to create an "app password", and use that to sign in instead of your normal password.

First, go to https://myaccount.google.com/security and turn on "2-Step Verification". Follow the instructions to add a verification method for your Google Account. Unfortunately, there is no way to avoid this.

Afterwards, go back to https://myaccount.google.com/security and select the newly-available "app passwords" option. Use the options provided to generate a new app password.

Finally, remove your Google Account from System Preferences, then add it back again using your newly-generated app password in place of your normal password. (I recommend completely removing and re-adding the account like this to avoid potential problems with sending messages in Apple Mail.)

Afterwards, you will once again be able to use Mail, Contacts, Notes, Reminders, and Calendar/iCal with your Google Account.

Has anyone found a solution that works?

I am running 10.13.6 on a mid-2011 21" Mac and, no, I cannot upgrade to a more recent OS.