How do I find my friends lobby on a custom experience?

I’m trying to join my friends server on one of the community made modes, but I can’t find his server. I’ve tried searching what he named it up with the same tags but nothing. Is there a simpler way of searching that I’m missing or is it just random?

I can’t join him from an invite and we’re trying to go on opposite teams and he said if I join we will be in the same team. If anyone knows a solution that would be great. Thank you!