how to make acapellas fit over a produced track

What I do is divide it into the verses and chorus parts. Then snap to quarter note (or even measure) and find the downbeat of the first measure. Mixcraft has a handy timestretch feature that works for me so I can tell it to automatically adjust tempo and it’s usually spot-on. After that it’s just syncing it up. If that doesn’t work for you, just find where the starting point and ending point should be and manually stretch it that far. I use that method a lot too…

Check out tutorials on youtube or read the manual, this is the 1st thing you should understand without thinking my friend.
I would understand you asking, but Logic is a serious piece of kit. Its a steep learning curve for anyone!

chop and stretch.