This guide applies will walk you through how to fix this error:
This action is not supported when you are signed in to multiple accounts in the same domain or on multiple consumer accounts. Log out and try again
This error occurs if you are logged into Google services with multiple accounts. It's functionally a variation on the known account management bug with multi-user login issues (see bug tracker). Both Google products: Google Sheets and Google Data Studio are affected by this issue.
To fix this error, you have two alternative options:
Solution type 1 - Log out from your Google accounts
Log out from all users from Google in your browser except for the one account attached to your Supermetrics license. Then try to log in to the data source again. To log out of Google accounts, please refer to this Google guide: Sign out of Gmail
Solution type 2 - Incognito mode
Alternatively, if logging out from all users is a hassle, you can also do this via Incognito/private browsing. Make sure that you log in with only ONE Google account (else the issue continues there too).
Star ⭐ the Google bug tracker
If you'd like to help speed up the fix from Google's side, please click on the star in this Google Bug report. More votes mean it goes up in their urgency. We appreciate your help.
If you continue to have issues after trying the above actions, please submit a request to support with the details of the issue and we will assist you.