My Google Playstore is working after following the instructions by Booxtor on a youtube video.
https://www.youtube.com/watch?v=Nd1rUSmFBVw
I have a Max Boox 2 Pro Limited edition (4gb ram) by the way, and I also have the international update too (based in Austria, Europe). But I can't reinstall my purchased apps which I already purchased. I use ESF explorer to backup the apps as apk before doing a factory reset for some reason. So what I do is after signing into google playstore connected to the purchased apps I install the apk files and this seems to work. Not sure if this method will hold in the case of app updates.