The switch does not appear. I tried everything. This is what the console says:
Error while compiling TurretSwitches: 'HashSet<PlayerNameID>' does not contain a definition for 'Exists' and no accessible extension method 'Exists' accepting a first argument of type 'HashSet<PlayerNameID>' could be found (are you missing a using directive or an assembly reference?) | Line: 171, Pos: 72

Add

using System.Linq;​

Added, but still the plugin reports the same error

add using System.Linq;

replace
return SamSite.GetBuildingPrivilege().authorizedPlayers.Exists
to
return SamSite.GetBuildingPrivilege().authorizedPlayers.Any
The plugin will compile, but I haven't tested how it works.

public bool CanToggleSamSite(BasePlayer player)
{
    if (TurretSwitches.config.RequiresPermission && !player.IPlayer.HasPermission(TurretSwitches.SAMPermission))
        return false;

    if (TurretSwitches.config.NeedsBuildingPrivilegeToUseSwitch && SamSite.GetBuildingPrivilege() != null)
        return SamSite.GetBuildingPrivilege().authorizedPlayers.Exists(x => x.userid == player.userID);

    if (SamSite == null)
        return false;

    if (SamSite.GetBuildingPrivilege() == null)
        return true;

    return true;
}


return SamSite.GetBuildingPrivilege().authorizedPlayers.Any(x => x.userid == player.userID);

In CanToggleSamsite, replace the last line that is above this text

still got that error