The size will be a little bit too small for an adult and the materials that the case is made from is more than likely particle board. That stuff wont hold up for much more than a year if you are lucky. You would be better off modifying a 10 gallon tank to stand on end to house the snake for the first year or two then step up to something like a 2 high x 2 wide x 2 deep cage that will be plenty for an adult.
One thing that is important and also makes housing ATBs trick is that they need high humidity but also plenty of ventilation or you will start a mold breeding project in the cage.
My cages are all heated with heat pads and it seems to work out nicely... the heat is sent up through the mulch which evaporates the moisture in the mulch. The moist heat travels to the top of the cage and collects there creating a warm spot for the snake. The bottom of the cage stays cool.
Have your cage setup a week or so ahead of time to allow everything to stabilize and give you adequate time to "tweak" the temps and humidty.
Oh a sidenote... it makes me feel great to see that you respect my input and information but there are a lot of great people floating around that could offer you advice. The title on your post is really limiting the views that the post and information that you get. The more people that give you information the better off you will be in the long run. (If one of the mods reads this can you please change the title too "Housing for an Amazon Tree Boa?")