when ever I download this game: https://pwalkerscrisps.itch.io/rtx-morshu-2d/download/eyJleHBpcmVzIjoxNjEyODI3MT...

right after it finishes downlading, the file gets deleted.

That's almost always caused by antivirus software. Does it happens with other games, too? If not, you might want to tell the creator, and/or have someone else also scan the file.