A1398 2015 - inadequate fan behaviour/noise
I understand how frustrating this can be when you set your expectations and they don't quite line up with what reality is giving you.

In my comments, I stated "If you want complete silence with performance, you bought the wrong product - you need a desktop with much more efficient cooling."  I know you're not expecting complete silence, but you've got the wrong product for the job you're asking the machine to do.  Here's why...

The most top of the line MacBook Pro from 2015 comes with an Core i7 CPU, 16GB of RAM and a discrete GPU, an AMD Radeon R9 M370X with 2 GB of dedicated VRAM

The GPU VRAM recommendations from Maxon Cinema 4D for the for the Cinema 4D R21 and S22 is 4GB.


  We recommend at least 4 GB VRAM for GPU rendering


So, the Mac that you've selected only has half of the minimum recommendation for this particular piece of the software.  You Mac has no other choice other than choice but to spin up fans to cool off due to the extreme load they now have to deal with.

So, yes, these are problems, but unfortunately, it's not a problem with your Mac nor can it be fixed.  Unfortunately, the 2015 MacBook Pro is not the right fit for your particular need.