I'm glad that you are keeping the older versions up; it really helps for historical purposes to see how much things have changed/improved over time. Please mark the old versions as 'obsolete' or 'outdated' or some other indication in the name on the itch download page so we know about it.
I can help with testing the download thing once it is live to make sure it works in the itch.io desktop application. :)
Work on what you can and focus on that, the rest will follow.