Azure B2B vs Azure AD Connect

What is the interaction between AAD Connect and B2B (MIM Graph MA)?

Szenario:

Customer has synced on-premise users and groups to AAD with AAD Connect.

Now he want do B2B collaboration with the mim graph connector.

Based on AAD groups he want set permissions to on-premises apps. Can we use

the existing synced groups? Do we have to create new AAD groups for guests?

What is the best interaction?