I spent a couple hours today watching how to videos and planning the video I was going to create with Premiere Rush, assuming that I owned a copy of it since it was installed on my system with my Photoshop subscription. Turns out, I don't. If I want to actually do something "fancy" with it (like have an audio track, for example), I have to buy a copy. I don't have the money for that.
You need to make it clear that this is a limited-feature install so people don't waste their time.
(Disclaimer: I'm a volunteer here to help and not an Adobe employee. I just wanted to clarify because sometimes frustrated new Community members aren't aware this is a user-to-user forum where sometimes Adobe employees who are identified by the Adobe logo and "Adobe Employee under their name do reply.)
You should be able to add audio even on the free version. What happens when you try to add audio? Are you getting an error message?
If it helps, they do post what's available in their plans: