Yes, just keep supervising their interactions.
You haven’t mentioned how long it has been since your GSD was fixed, it takes a few months for the hormones to clear out of his system.
I suggest when you let them be together you leash him and leave her loose so you can control him and don’t let him make boisterous play advances toward her. She may feel scared of this larger and more boisterous dog and needs to get to know him and learn he can be trusted to not hurt her - if he can be trusted to not hurt her.
Because they are male and female and will be reasonably close in size I think if you handle this correctly they will eventually be best friends. You have also not mentioned how long you have had the pup. This will all likely sort itself out in a few weeks. Be patient, keep supervising and be positive. you may also want to get involved in their relationships by pulling their focus to you for yummy treats. Do not do this if either one of them shows any sort of food agression.
Most dogs will “self handicap” when playing with a smaller / weaker / younger dogs. I have two dogs, a 50 lb and an 11 lb, both adults. When they play the larger dog often lays down and the smaller dog crawls all over her. Sometimes the larger dog will get really excited and stand up and jump around and continue to be boisterously playing, at that point the smaller dog will keep playing, but go under a chair or some other furniture object. I have also seen this many times at the dog park where a larger or stronger dog will “even out” the disparity in order to play. If your Shepard isn’t doing this, watch carefully that he doesn’t hurt the smaller dog. You can encourage him learning to do this by keeping him calm during their interactions.
Dogs that are removed from their litters early or that don’t get to interact with other dogs often are “socially handicapped” in their relationships with other dogs. Pups learn a lot during their first 8-10 weeks with their mom and siblings and that is important stuff for good dog on dog relationships. Dogs that are isolated from other dogs also don’t get to practice their social skills so can give out improper signals or not be able to read the signals of other dogs.
When I introduced my two dogs it was a very very active 50 lb. adult and a 10 week old 3 lb. puppy. Because of ther age and size difference they were NEVER left alone together. Either I was there, physically right there closely supervising, usually with a hand on one or the other of the dogs, they were in separate rooms or one of them was in a crate. Usually it was the puppy in the crate, she was a bottle baby (found newborn abandoned in a gutter) and LOVED her crate, so when I had to leave the room or while I was working and they were in the camper on my truck (think giant luxury dog den with beds, pillows and toys) I’d have her in a big crate for her own safety - so the dogs could be together but the little one could not be crushed or injured. By the time she was a few months old and several lbs. they were best friends and could play unsupervised.