Waterfall) The command "/send" doesn't work

When i command it, the server send messege that i haven’t permission. But i’m OP and admin.
Command “/server” works well.
I tried to use Luckperms plugin, but it supports only Bungeecord, not Waterfall…
What i have to do?
I want to make command block(and connected pressure plate) support normal players to change the server, without command.

Bungee commands are proxy related, they can’t be executed from a spigot / paper server, like commands blocks that are not in communication with the proxy, unlike players.

Luckperms works perfectly on Waterfall.