It’ll work eventually, I hope! Arma II is a 7GB+ download and beware of your free space while it installs. You’ll need twice that space because it installs from a zip file.
Every time I tried to run it I got the error, “G001:I’m sorry there appear to be some files missing.” Unfortunately Capsule wouldn’t let me uninstall it either. I fired off a support request but in the meantime I discovered where the game files are downloaded!
To fix it, I renamed a directory called “game_root” in C:UsersmylocalnameAppDataLocalGreen Man GamingARMA II – PC and restarted Capsule. I’m not sure if renaming the directory or restarting Capsule fixed the problem but it’s installing the game again and it recreated the game_root directory so no harm done. Phew.