HALO MCC not installing

Hi all,

Trying to download MCC and have had it installed before but apparently I need to re-download the whole lot to play it.
Problem is, it doesn’t matter how I download it, it doesn’t work!!
I’ll press download, it’ll think about it for maybe a second, and then just say “install” again.

It doesn’t matter what drive I try to save it on, I’ve tried downloading on the Xbox app and the Microsoft store and it’s just having none of it. I’ve restarted my PC, downloaded all of the windows updates, tried finding if there’s an old copy still on my PC that it is getting mixed up with and… nothing!
Anyone able to shed some light on this for me please?