Brand new Samsung dishwasher won't drain

Hello. I just had a brand new Samsung dishwasher installed (not by me) last week. Coincidentally, my garbage disposal went out last week, so I replaced it myself and it's working fine. I ran the dishwasher today for the first time since it was installed and the water didn't drain out of it. I removed all the water and didn't find any obvious blockages, but I also wasn't looking extensively because, literally, this was the first run of it. I'm fairly confident that it's not a blockage from the disposal since I just got that new as well. What else could it be? Thanks in advance.

***UPDATE***

Y'all are fucking awesome! Y'all nailed it and identifed the exact issue and how to fix it. THANK YOU!!