Have you ssh access to the server??
Discussion
I believe I do. Is it possible that way? I'm not a techie, I just fumble my way through it
Presuming a few things here, but worth a shot.
sudo chmod -R 777 /path/to/webroot/
Then try moving the folder in with the file inside the folder. Winscp will do this for you. Use your ssh credentials to connect.
Once it’s in place run
chmod 664 /path/to/webroot/
This changes the web root permissions back to unwritable.
./well-known folder should still be 777 permissions.
In Winscp you can right click the file and check permissions.
Hope this helps.