Even if you don't have a paid Prime membership, you can still access new releases through (formerly IMDb TV).
Looking for something new to stream without paying extra? Here’s what’s recently landed on (included with your Prime membership): new releases on amazon prime free
Scroll down the home page to the row titled "Recently Added Movies" or "Recently Added TV." These are the newest additions to the free library. 🚀 Don't Forget About Freevee Even if you don't have a paid Prime