MEVO & the Grooveriders

The achievement description is rather unclear. To unlock this achievement, you just need to keep your combo under 25 (never go over!). However, you CAN hit more than 25 notes in a level.

I played on level 5, and kept hitting notes and breaking my combo between 5 and 10. The highest combo I ever got was 10. Completing the level after never going over this will guaranteed yield the achievement. I could've sworn I'd done the same thing and kept under 25 a couple times, but to my understanding, the achievement does not trigger on levels 1-3 nor tutorial A.