Yeah it’s not obvious on my domain which just allows you to add CNS Names or whatever, there’s not FTP as far as I can tell.
The end goal would be something like https://www.fakewomanwould.com/.wellknown/nostr.json. How you get it there depends on your access and software. If it was me I’d just do a file transfer. If you have software that deploys the whole site it might get removed, so you’d need to put it in with their code (such as in a repo like that page describes)
Discussion
It needs to be on the server itself, it wouldn’t be through DNS. Your “hosting provider” (might also do your DNS, but might be separate) is where to look to see if it has server access available at all. If they provide you a full blown CMS (content management system) and never obviously offer server access then you might have to ask their support team. They likely can drop a file in if you need it. This file (format in that article) has nothing but public info and the point is to post it publicly, so you don’t have to worry about chain of custody or anything.
Thanks Russ — will contact them.