That's a good result! This question bank is not adaptive, nor is there a set time limit, so it's not possible to provide a score that would equate to GMAT scores (or even to percentiles, since there's no time limit—time management is a big part of these kinds of tests). But 20/25 is good.
The takeaways are around the following:
(1) For the ones you missed, can you learn how to do any of them? I'd be concerned about learning the 5-6 level. I wouldn't worry so much about the 7-8 levels; you can't win them all.
(2) How was your timing on the individual questions? Any opportunities to shortcut any of the solutions / learn to work more efficiently?
(3) Are there any you got right but used so much time + mental energy that you'd actually rather get that problem wrong fast on the real thing? What are the characteristics that made this problem so annoying for you? (In other words, how are you going to recognize when you see something similarly annoying in future so that you can Get Out Fast?)