The 20-year-old has linked up with the Pilgrims until mid-January initially – making him available for United's next nine National League North encounters.
Sotona, who will wear squad number 17 for the Pilgrims, featured for Doncaster at the Jakemans Community Stadium in pre-season – having begun his career with spells at Manchester United and Burnley.
He is registered and eligible to face Chorley on Saturday.