Recently I have encountered multiple issues with 3rd part access to our Sharepoint workspace.
The message they shared says:
AADSTS90072: User account 'user.account@e-mail' from identity provider "https://xxxx' does not exist in tenant 'company-intranet' and cannot access the application '00000003-000-0ff1-ce00-000000000000'('Office 365 SharePoint Online) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account.
How it can be solved please? I'd really appreciate any leads, ideas, workarounds