These are their Add-in rules:-
https://damassets.autodesk.net/content/dam/autodesk/www/adn/pdf/desktop-app-submission-process-overv...
They don't say what their preferred method actually is. There's a delay before they publish updates (about a month I think?). If you ask them, do please let us know what they say - I rolled my own (happy to share with you if you like - it' fully non-blocking and very powerful, and requires user consent of course) but I'm wondering myself about whether or not they might frown on that. I'm only planning to use mine if there's something show-stopping that needs to be fixed ASAP, otherwise I'll just use their store.
FYI - it is a *major* pain to get your own updates to work properly - Mac and Windows are *very* different, as are different user environments and settings - rolling-your-own is *very* complicated, and exponentially more if you want to go non-blocking and not break anything if networks are down, and all that with a cherry on top be fully secure as well!
What are you writing? If you're planning to make it free, and want to do a collaborative release of a general-purpose add-in that makes it a no-brainer to add cool extra features to Fusion360 ... I've got a half-baked plan that might perfectly suit you - updates and all.