How to play "private" match on maps likeMeta Raid

Games Other Halo
1

I seen a video of someone on the map meta raid which is husky raid, by himself and I was wondering how do I play maps like that or rain by myself cuz I can’t seem to find it was exactly maps at all other than playing online multiayer?

2

Sounds like this can only be done in customs.

3

I can’t find themap in custom though

4

Grrr. I cant find ANYTHING about it ANYWHERE