Yeah, I was able to buy it after all. All I had to do was go on a video call with other creators, kvetch a little about how I wasn’t able to, and then the magic spell took effect and suddenly I could buy it. Note that I’m not actually embarrassed by that: everybody on the call was intimately aware of the phenomenon.
Anyway, first map. I can tell right now that Dungeon Draft will work fine, once I figure out what assets to acquire. I don’t need fancy, I just need floor plans.