Hello,
I can understand that you want an application (or two, one for only regular users and another for admin), you want something similar to social media (not completely). And I have a theme design your work. If you want to look at it, I can send you.
My idea behind the work -
1. There will be a sign up page where user can choose admin or regular user. (If someone tries to sign up as admin then "super-admin" will check the user data to see if it is one of your company's admin or not).
2. Login page will be regular, and I will check if user is admin or not from database.
3. There will be two tab (you mentioned three but I can't figure out three tab from your description) in main activity. One will be feed (like facebook front page) second will be profile. (In the feed page, user can see other users posted image or article. Also he can upload.)
If you want a complete separate app for Admin, I can manage that also. Also, if you have a theme show me, I will work that way. FYI, my skill is in Java.
I have worked on similar project earlier, (I don't have the code since it was 2 years ago). So I have little bit skill on the project you're interested in.
Istiak