I'm not sure how subscribing to referees work but I'm pretty sure that when you subscribe to a Workshop creation in FPWW it is treated as "retired". Steam also tends to sometimes take a while to recognize a Workshop mod too. Either try giving it a few game resets and matches or try looking at the Team Edit and referee options and try to figure out if you can find him there.

I subscribed this but there's no way I can find it..