"This app is blocked" error message usually indicates that oAuth has not been configured correctly for the workspace associated with that account. No worries! We're here to help you resolve it. 👇
First, try this method: Log into Instantly from Incognito mode. Try to add the Google account again.
If Incognito doesn't help, please follow these steps and double-check that oAuth has been enabled for all your domains/workspaces.
Kindly login to your Google admin account https://admin.google.com/
Go to the "Users" tab https://admin.google.com/ac/users and double-check that the users you are trying to connect to Instantly are listed there:
Go to the API Controls - "Manage Third Party App Access"
Make sure the oAuth has been enabled for all the users on this workspace:
If oAuth isn't set in this Workspace, this article could be helpful: