There is no conversion table. You can look up some of the more recent DAT breakdowns where people have posted what they were getting on Math Destroyer vs the real thing, that’s as good as it gets.
I was averaging about 32/40 I think on Math destroyer tests. I think Lowest was 26/40, highest was 38/40. Got a 30 on QR. don’t use Destroyer as practice tests for a score, use it as content review and practice. Just make sure you’re comfortable with all of the problem types in Math Destroyer and learn from what you miss