Sapodilla is also known as the brown sugar fruit because it is super sweet and has a malt-like texture. Sometimes when people find this fruit in their box, they mistake it for a potato! It can be hard to tell when a new fruit is ripe when you've never had it before.
This is why we have a ripening guide to help guide you. For sapodilla and most fruits, you'll want to press on it all over and it should be soft everywhere you press- kind of like a boiled potato! ;)