How do I make Romano-British playable?

I was playing as the RB and for some reason it doesn't work, when I play as them I immediately go to the bottom left hand corner of the map and the game is locked in an end-turn sequence. Can anyone tell me how I make the Romano-British playable? Thanks.

Have you edited the descr_strat.txt file in the campaign folder so they start with their own family and settlement? If you haven't, it's impossible to play as them.

My mod: https://forums.totalwar.org/vb/showthread.php?t=54943 lets you play a provincial campaign as the Romano-British.