@AcesWild5049 Usually this is nothing on your side. Might be a temporary server issue. I have successfully tested posting some seconds ago, so please test again.
Be sure to have set up a correct topic-id.
@suprise-attack When you click reply, a window will open up. Beneath where it says “Replying to …” there are a series of icons. The one farthest to the right is to upload an attachment. You can add your game file as an attachment to your post. I think it works anyway. I haven’t got a reply from my opponent yet lol.