i cant use command "/mvcreate flatworld normal -g CleanroomGenerator:40,stone_bricks"
it's my problem or plugin? and i was trying to put . somewhere to dont have bedrock but idk where

I'm going to close this old issue as I assume your lack of response means you've gotten it working. Feel free to re-open if that's not the case.

btw i'm playing on newest version of plugin on 1.16
paperMC (this paper spigot bukkit engine)

Needs to be | not , and I'm not sure if just stone_bricks is good enough or if it needs to be the full minecraft:stone_bricks name.

If you want no bedrock too you'd want this /mvcreate flatworld normal -g CleanroomGenerator:.40|minecraft:stone_bricks