I would make it a condition of paying the deposit. You are paying for some of his college, right? Maybe you can go to the office with him to register. Procrastination is something he probably suffers with.
From what I understand you are also going to need him to sign a FERPA waiver before you can talk to the school or have access to his grades so get that signed as a condition of your financial contribution.
Maybe you can text him twice a day to remind him to take his meds? I found it easier to get those Mon-Sun pill boxes that are usually for senior citizens. I load them on Sunday and can tell at a glance if a dose is forgotten. I am assuming he takes medication; ignore advice if he’s not.
My daughter has similar issues but is only a h. s. sophomore. I can’t see a day coming where she doesn’t need a reminder to take medicine or do school work.