SSO with Mobile App: No redirect after authentication

After configuring Entra and Zoom for SSO, I attempt to sign-in with SSO from a Zoom Mobile app on iOS.  After M365 auth, there is no redirect back to the app with a valid session.  I see an option for Relay State (URL) in Entra's SAML configuration page, but I am not sure if that is what I need and, if so, what is the URL?