Hello Shimon,
While testing the plugins available here, I could make the other integration work with Maxwell 4 using this patch here: Maxwell Render integration for Blender (different one) - #619 by pwquint
It works with Maxwell 4.1.1.1 and not with 4.2.1.3.
Here is Maxwell Render 4.1.1.1 for OSX: https://drive.google.com/file/d/1KvtUMvT2H5RBNho8bUJjOM2kJ6yc0Zfg/view?usp=sharing
And here for Windows: https://drive.google.com/file/d/1KwZI6PEmIQc4q357UHOf85DtiQ7eKVW5/view?usp=sharing
Cheers!