Bit of an old thread, I know, but we had this issue at our company and we had to run the following Powershell command against Azure AD to resolve it:
Set-MsolCompanySettings -AllowEmailVerifiedUsers $true
https://support.office.com/en-us/article/Power-BI-in-your-Organization-d7941332-8aec-4e5e-87e8-92073ce73dc5?ui=en-US&rs=en-US&ad=US#bkmk_preventjoining
It might be an uphill battle to get the council to run the command against their Azure AD, so the easier option might be for Microsoft support or the software reseller to delegate access to an account on a different domain.
