A playthrough requirement is the number of times your bonus must be wagered before you may withdraw any profits. As an example:
Your preferred Michigan casino app gives you a $200 free wager.
They may force you to play (wager) that money twice before you can cash out any winnings from following bets.
Some casino applications demand one playthrough, while others may ask you to play through multiple times. Examine the specifics of your bonus.
Please keep in mind that playthrough requirements usually apply to your first deposit as well. That is, you must play through your initial deposit before you can withdraw any funds.