In my own case, I found it helpful when my mother offered to take me/go with me to my psychiatrist. Especially when it was difficult to communicate what was really going on. My sister also went with me to 2 therapy sessions, a place I felt safe while sharing my diagnosis with her.
Perhaps you could offer to go with the young man in a support role. Encourage him to do what the doctor says. There are many reasons why this young man might not be compliant -- paranoia, social phobia, delusions, lack of insurance/money, or simply not being aware of his need for treatment. Many communities have county/community mental health organizations where you can get him connected with local providers and possibly group activities with his peers.
But you may be the key to getting help for him. I admire your interest in him and your willingness to seek help.
Carolyn