Late response seeing as this was posted a month ago but do the main quest "THE SECOND DREAM"..
you can’t “find him” but he normally spawn 2-3 missions after you kill a boss. eg. Jackal, Cpt. Vor, Lt. Kril
There is no real way on finding him except if u use the beacon. Otherwise it's just luck based when he spawn. Usually when I run lvling missions he appears on a 86% for me n the ppl I'm up with