So weird that Firefox downloads as ".tgd.txt" if I click "open" but downloads as ".tgd" when downloaded. This was happening on last install of Windows. Just must be how Firefox does this now? Weird...
First thing I'd do is change the fog quality to 1, and then voxel scattering quality (GI Settings -> GI in Clouds) to at least 500.
Additionally you don't have defer atmosphere checked, so MPD is effecting cloud quality severely. Unfortunately this means much longer render times, but for the cloud quality, may be worth it. For it to be truly noisless you'll probably want AA7 or maybe AA6 with custom sampler with lower noise threshold.