First of all, congratulations! It’s so sweet of you to have taken her in, and that you’re a concerned bunny “parent”.
Post-adoption, there are a lot of little kinks to work out because bunnies are smart enough to know what to expect from someone, and if things weren’t great at the last place it will take time for her to understand that her expectations can be different with you. 100% agree with tobyluv. That’s exactly what worked for Demi (although she’s cageless, so in her case it was the laundry room). Bunnies are naturally curious, so if you just leave the cage open during all of playtime and just sit on the floor outside the cage and watch TV or text a friend, she will eventually want to explore beyond. So for a week or so, just make a date with the floor maybe 5-8 feet from her cage. Be sure to have a piece of lettuce or cilantro handy for when she comes out.
Another thought is, like Luna said, you could tear up a few pieces of kale and make a Hansel and Gretel-style trail starting juuuuuust outside the cage. Just to remind her that she can leave if she wants to! Don’t want to rely on that though, we wouldn’t want to “overcondition” her!
Have fun getting to know your girl!