I got June when Cash was more than two years old. It has only been about two and a half weeks, but they are getting along just fine.
June is in the expen when I am not here and this allowed Cash to get to know her without risking her getting too close and upsetting him. He still gets very cranky when he is sleepy and she wants to play, but I am hoping that this will get better.
Just today, I told Cash off for snapping at her for the hundredth time and Cash sulked for the whole day! He was like: "If you want to take her side, you aren't on mine."
I cuddled and trained him later (he absolutely loves his clicker training) and now they are playing blissfully in my room (they like the carpets and she is wearing a diaper, so it is okay).
I think you need to restrain the puppy from dominating your older dog. Like the other posts said, you need to teach her what is acceptable and what is not. If she gets too rough or out of hand, call a time-out and put her in an enclosed room or pen.
Also, I have separate toys for them and although Cash lets June play with his, he is always in control and holding the toys. He just teases her and makes her run after him. He is a great babysitter!
June has her kong and two stuffed toys in her pen and they aren't for communal play. They are hers and the other toys belong to Cash. It helps to establish such boundaries.
Good luck. You will get some great advice on YT!!