We're using fieldMaps with ArcGIS Online and ArcGIS Enterprise. Authentication is based on oAUTH (SAML with Azure AD).
When the user needs to switch the organization he is forced to sign out (which might be OK) but he not only needs to re-authenticate into ArcGIS Enterprise (or AGOL) but also to the oAuth Provider (Azure in our case). Many clients alllow to keep the oAUTH authorization state (token) but fieldmaps (on iOS) does not.
Please keep sign-in information inside the app so that the user does not need to enter all his credentials.
Even better: allow an easy way to switch between Enterprise and ArcGIS Online when the user is the same and already signed in on both sides.
