ArcGIS Field Maps returns a provider error:
"The Trimble device failed to start".
The issue only occurs in mobile devices, not when using an iPad.
Selecting the Field Maps folder while setting up the connection does not allow the application to make the connection to Trimble Mobile Manager.
When browsing to the folder on the iOS device, select the 'Mobile Manager' folder instead of the Field Maps one. It may be necessary to uninstall and reinstall either Field Maps or Trimble Mobile Manager to get the folder selection dialog up again.