https://tesrenewal.com/search/node/Dark%20Brotherhood%20term%3A4


https://tesrenewal.com/forums/morroblivion-development/start-tribunal-at-level-1


https://tesrenewal.com/forums/morroblivion-problems/tribunal-and-bloodmoon



Doesn't happen until you  complete the Main Quest, or Become  a Master in 1 of the Guilds,Example(fighters,Morag Tong ), or Master in 1 of the Main Houses. ( House Telvanni,House Redoran)