Hi All -
I'm one of the co-founders, our phpBB mod hasn't been updated to include avatar support. We haven't updated the mod, simply because phpBB's AutoMod and other mod-architecture is difficult to work with so our (very!) limited resources are better spend on other platforms.
If you're willing to update our Mod, you're welcome to 6 months of free service (any package). Please email us at support[at]envolve[dot]com if you're interested in helping.
You can get more info on our API here: https://www.envolve.com/docs/api.html