The left-sided defender, who turns 24 on Thursday, has been training with the Pilgrims following recent spells with Mansfield Town and Worksop Town and has now put pen-to-paper to join United.
He initially progressed through the youth system at Notts County before moving to study in America — where he played for New York and Long Island Rough Riders.
Craven is available for selection ahead of Saturday’s trip to Bradford Park Avenue — although he is cup-tied following previous involvement in the FA Cup with Worksop.