Getting to the ESO Dark Brotherhood Questline isi pretty much exactly the same and the Thieves Guild DLC! You can get the first Dark Brotherhood quest from your collection screen, or visit your nearest Outlaw’s Refuge. Also, the main wayshrine in Kvatvh will be open for you to fast travel to -- or you can fast travel to a friend or guild member!
I hope you enjoy Elder Scrolls Online Dark Brotherhood Guild! It’s going to be another amazing DLC!