@Agolphin
B2C is specifically used for consumer based applications that allow consumers to signup/signin using their social identities in order to login to the application. What you are trying here is something different, which cannot be achieved by using B2C.
We have documentation to federate GSuite(SP) with AAD(IDP) here: https://learn.microsoft.com/en-us/azure/active-directory/saas-apps/google-apps-tutorial.
You need to look for a documentation from Google on how to add AAD(SP) with GSuite(IDP).
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