I think the easiest way to download apps not in get jar is to use dropbox. Use your Vox browser and go here:
https://www.dropbox.com/android You can directly download the dropbox app which will land in your downloads folder. If it doesn't begin to install on its own (I honestly don't remember if it does) go to downloads and click on it. Dropbox will then install.
Once it is on both your desktop and on your Vox, you can locate the apk you want, download it onto your desktop dropbox, and then click on it on your Vox Dropbox and it will install. You can find apps by searching, but there are some stores folks really like. I like handango.com because you can also buy paid apps from there and the files are all legit.