I've tried to download forge a couple times, and both times it has given me an error. It showed the error twice, at the same place each time. I believe it was right after the pillager outposts line.
I've attached an image of the error, and here is the log : https://pastebin.com/pC0KhYja
Sorry if this is too little info, I'm very, very new to this and read the rules as thoroughly as I could.
Edit : here is the installer log, I am sorry for not providing it at first - https://pastebin.com/ALiiNGHm