Error while compiling RaidProtection: 'ulong' does not contain a definition for 'userid' and no accessible extension method 'userid' accepting a first argument of type 'ulong' could be found (are you missing a using directive or an assembly reference?) | Line: 1075, Pos: 83

the right way to fix this is 
find complete line

replace with
HashSet<ulong> AllOwnerIdsTemp = (from id in priv.authorizedPlayers select id).ToHashSet();

so basicly remove only the .userid from the line. hope it helps ya out