Pit of the artificer and ARTIFACT

diablo 4 pit of the artificer I AM USING SEASON 3 CHAR AND CANT ACCESS or find the rune either in scosglen or anywhere else does it no t work except in season if so why

Season 3 is over, that character is on Eternal.

You need to first complete a NMD 46+ to get the materials to start the Pit, then you need to go to Cerrigar (Only town with Pit in it) and interact with the obelisk to start your first run.