It doesn't sound like you did anything wrong, unless you forgot to dechlorinate the water. You didn't mention that, but I assume if you did enough research to set it up properly, you wouldn't fall down on that. Red-Eyes can be delicate, definitely important to get captive bred animals, the older the better. Dumpy/White's tree frogs are pretty much bullet proof. Although many WC dumpies adjust well to captivity, I still recommend purchasing captive bred frogs. One change you will have to make to your set-up for either of these tree frogs is 6-8 degree increase in temperature during the day. Appropriate daytime temperatures for a dumpy is 76-85, never exceeding 89. A nighttime temperature drop is appropriate, but don't let it go below 65.
I recommend Josh's Frogs as a source for either of these tree frog species and for a new mossy frog if you decide to try again. I've gotten a lot of great tree frogs from them of a variety of species, and all of their frogs are captive bred. Here is a link:
https://www.joshsfrogs.com/animals-f...ree-frogs.html