Initiate of Mysteries

Initiate of Mysteries is a side quest in Fallout 76.

Quick walkthrough
The goal is to find one's mentor in Lewisburg. Her remains are located amongst several creatures on the main thoroughfare, in the midst of the vendor booths. She's behind a display of paintings, near a display selling birdhouses on W. Foster Street.

Detailed walkthrough

 * After accessing the facility beneath the manor, one must use the terminal to receive the Order of Mysteries - Rank: Initiate holotape. After listening to it, the player character has to request a mentor assignment from the terminal, which will require them to travel to Lewisburg and find Mistress Natasha Hunt.
 * Lewisburg is located in the northeastern Ash Heap, directly southeast of the manor.
 * After discovering her remains on W. Foster Street, one can find a holotape and a login with password for the mainframe on her body. The holotape will reveal that she came to Lewisburg to hunt raiders who were preying on the Order. To complete her assignment, find Kerry's body on top of the building opposite the one where Hunt was. Pick up Kerry's orders to complete the optional objective.
 * To continue the questline, one has to promote themselves using Hunt's login details, then relog as themselves. Hunt's login grants access to the infirmary and council chamber terminals, as well as the ability to fabricate the Garb of Mysteries from the fabricator. The promotion starts the next part of the questline: Novice of Mysteries.

Bugs
When trying to turn in the final part of the quest, when you log back into your account on Cryptos for the promotion, spam your spacebar key on your keyboard or jump button on your controller to get around the bug or you'll be stuck on the final part otherwise.