Oh, I didn't see that since I stopped flashing before that message even appeared because unrelated to Davidc502 there were breaking changes in the LEDE version line itself. The fortified ROM I mention has it's own OpenWRT forum BTW: Davidc502- wrt1200ac wrt1900acx wrt3200acm wrt32x builds
I'd go with a standard one first (non fortified) - that's what I did few years ago when I got my 3200 - and then you can switch to a fortified one if you are adventurous or like security like me. Always follow any tutorials very precisely and carefully and unfortunately custom ROM flashing can have a risk. Despite that I'd never buy a non OpenWRT supported router and I'd rather brick a router than rely on factory ROM which have gaping security holes.