I did this to get AVA to run from Steam:
1. Get a fresh copy of AVA steam and install
2. Get fresh copy of Aeria AVA and install
3. Run Aeria AVA once to make sure that it works
4. Once confirmed that it works, go to the Aeria AVA game directory. Should be something like C://AeriaGames/AVA
5. COPY all of the files inside the AVA folder.
6. Go to the Steam AVA directory at C://ProgramFiles/Steam/steamapps/common/ava
and paste the copied files from the Aeria game. It should overwrite pretty much all the Steam files, which is ok.
7. Now try to run AVA from Steam.
Please reply if this worked