The staging process fails with this error during the "Synchronization: users" step:
The data synchronization process has encountered an error. The Site Factory (https://www.xxxxxxxxx.acsitefactory.com) already has a separate account with the provided "name.surname" username (uid: XXX) which conflicts with the requested uid (XXX). There was an error while attempting to synchronize the core user data. There was an error while attempting to synchronize the TFA user data. There was an error while attempting to synchronize the miscellaneous user data.
You need to login into the destination Site Factory and delete the user profile. Then re-try staging.