Well my experience with adding an AU, it will show up on their credit reports. I applied for and received my Discover card last month. During the process, when asked if I wanted to add an AU, I added my boyfried. I was only asked for his name, nothing else. I figured it'd be great for him to have a card so I could have him run errands for me when I work late. 
I just assumed his status would be like the "Authorized Buyer" as stated from what that Discover rep told you. However, the account reported to his credit report at the same time it reported to mine (about a week later). I never provided his address, SSN, or even birth date. He does not have an inquiry listed either. Also, I used my mailing address (which is a UPS Store mailbox) for my application. My boyfriend also has his own mailbox at the same location, but we have different mailbox numbers. I guess Discover make a partial match with the street name and number and figured it was a good enough connection.
So I can verify from my experience, that just adding an Autorized User (name only) can be enough to have it report on the AU's credit report. 
Angel G.
Make sure that your address matches that of the primary cardholder... I found this was what was needed to get my DH's AU Discover to report as well as his chase card. Did this by adding him to Zync, which updated his address on Credit reports... After Zync started reporting, Chase and Discover followed suit
FICO 9: 
Filed Chapter 13 on 6/1/2017 after job loss. Discharged 6/1/2022.
Goal: Gardening!
Filed Chapter 13 on 6/1/2017 after job loss. Discharged 6/1/2022.
Goal: Gardening!
