Human Design seems like unscientific babbling to me. First of all the connection to astrology should already be a huge red flag and it mixes random stuff and magically we come up with four personality types (then later a fifth one is "discovered"). Shockingly these can be arranged into exactly twelve profiles.

It may be surprising to you but as someone who is well read in mentalism I can fairly confidently tell you that a 95% match is not hard to fabricate in readings. Admittedly is the area of mentalism I don't perform but I have read plenty of theory. Your HD reading was probably based on Barnum statements/cold reading. If you're interested to learn more about this I'd suggest "The Full Facts Book of Cold Reading" by Ian Rowland. For a more fun exercise, get a reading at a medieval fair or from some "medium" (please don't pay a lot) and compare it to your HD reading.