It does not allow to add permissions

[javiburatos]

When you try to enter a command it tells you that you don't have permissions. When I try to introduce them through plugins they do not detect such permissions as: demfactions.faction.default

[jtljac]

Are you using sponge for permissions?
Factions does not yet support sponge, you could try a forge mod for permissions
I am planning to support factions in the next major update, but there's no guarantee that'll be released soon