Converting Domain from Managed to Federated - Google Workspace IdP

Hi Team,

Just need some help here to setup SSO between Microsoft 365 and Google Workspace, where Google is the IdP.

Initial issue: Cannot sign into Office 365 with Google credentials (screenshot below).

After following Google articles and Youtube videos on fixing both Google & Office365 settings, I've arrived at the issue below:

What I now understand is that because we don't use Azure AD, there is no server for me to log into so that I can convert the domain to federated.

Is there a way I can federate a domain without ADFS?

Thanks

Fred