Maxwell does not support modern GPUs. The 40 series is not officially supported, the 50 series is not supported at all. Besides, older GPUs only work with CUDA, not RT cores. I didn’t want to write about the Bella renderer right away. 
But if the user wants the visual quality of Maxwell, there is nothing else but the Bella renderer. Unfortunately.
Yes , the forum is dead, and the specific french forum is dead too…
Not a good sign…
I ask for a request. Will keep you informed. Strange because they made an new release this March
Will look for Bella… But I liked so much the light mixing editor 
The new version of Maxwell renderer hasn’t been released for a long time. Maybe they just fixed the functionality of the Rhino plugin. It’s been working very poorly for years anyway. Try Bella renderer. It has the same quality (or higher), is much faster, cheaper now, a much better plugin for Rhino, and is under active development by the former Maxwell renderer developers. 
You are very convincing ! Will try it !
I thought taht THEA was also born from MX developpers
Thea has been on the market for a very long time. And it is still developing, although probably not as fast. But now version 4 has been released, which is very different. The unbiased modes (quality similar to Maxwell) have disappeared and the very fast Nitro GPU engine has been added.
So I have an answer from Fernando who is still behind the kitchen…
For Mac (M1, 2 chips) users, you have to install Rosetta 2 through terminal.
This will allows you to start Rhino 8 with (you ave to tick the option in the information window from the finder).
So far, everything is running ok . Only the «fire» preview is not “working” real time
Hope this helps
I have to say that the Fire preview mode is one of the reasons why I uninstalled Maxwell render. This preview mode of the final render was relevant 10 years ago. Nowadays, the Fire preview is absolutely inadequate. Low preview resolution, the final render is often different than the preview mode, still very slow. When I compare it to the Bella renderer preview, it is completely different. Bella offers the Saturn solver, where the preview in Rhino is exactly the same as the final calculation, it has an implemented denoiser, the preview is significantly faster than Maxwell’s Fire and works better in all aspects. Fire shows how Maxwell is extremely outdated today. Of course, other rendering engines (Thea, V-ray) also have quality preview modes today.
I really loved maxwell which is why I now use Bella Render. My understanding is it is the old development team, under new management more or less.
Yes, the original Maxwell developers are now developing Bella render.