Hi Hevedy,
I’m quite new to ue4 and saw this plugin, it looks amazing and couldn’t wait to try it out, but I kept getting rebuild error with 4.25 (try rebuilding manually, it says), so silly me read your post and thought I could single digit change the version number in the .uplugin and force install it to no avail, ofcourse 
I would really appreciate if you could let us know how you upgraded the plugin version from 4.15 to 4.21, and I’d be more than happy to contribute by upgrading the plugin version myself every once in a while and upload it here when a new ue4 version gets released!!
Extremely thankful for your great work Hevedy and Ali Akbar, can’t wait to use this plugin!! 
Sincerely,
Josef (an ambitious newbie in ue4)