You're not going to like my answer.
Rosetta is not intended to be accessible to the general public. the complexity of the codebase and of the biophysics means that it is typically learned through mentorship and academic training.
If you are really interested in pursuing it, check the faculty list on the Rosetta Commons website, and start emailing professors asking to volunteer as an early career scientist.
You will have so. many. questions. at every step. it's just... you'll be so much more successful if you have mentors to guide you.
You may be interested in foldit standalone. It's the more options version of foldit. With foldit, you can work on real biological problems in a training setting. You might be annoyed by this because you want to program, but getting intuition for the structural biophysics is step 1. foldit was explicitly designed as a training tool for people (like you) who do not know about rosetta. Using foldit will teach you about the score function, for example.
Everyone starts with foldit. I started with foldit.
Getting good at foldit will increase your chances of a Rosetta professor agreeing to mentor you.
If you are an undergrad, there is a Rosetta Commons mentorship program about to become active - please join the Rosetta Commons forum and inquire there for info.
If you're being asked to do this for some school thing, it's absolutely ridiculous for someone to think you could do it without at least several class days about it.
In summary - I strongly encourage you to reach out to the Rosetta Commons faculty and mentorship program if you would like to seriously pursue Rosetta.