I have had a quick search and can't easily find any documented technical requirements to be able to use AVA, so you might assume that it's optimised for all common browsers and recent versions of those. One online forum moaning about AVA cited a number of people moaning that Chrome wasn't working but none directly saying Firefox wasn't ok. But plenty of people saying they couldn't get through to an agent despite waiting and the system was overloaded. Hopefully you can get through to an Allstar Agent soon.