Hi Zoe

Good luck with these when you get them they are great frogs! to keep humidity up I have pieces of glass or polycarbonate over the mesh on the top and that seems to do the trick!
I actually have 3 in the same size exo - have recently redone it so still bit of growing in to do:



Theres a little pool at the base of the waterfall which they love (as well as the little cave I built into the waterfall itself) but with plenty of points to leave the water and some plants (anubias and Salvinia Auriculata):



And one of the inhabitants - azureus are great darts, bold and hardy: