I run the main organ and the transept organ on a 64GB Windows 10 machine with no problems.
As there are a number of options for number of audio channels and whether you want wet, dry or surround sound so it is probably worth reading the details on the SP web site and deciding which configuration you want to run.
See https://www.sonusparadisi.cz/en/organs/netherlands/rotterdam-laurenskerk-main-organ.html and click on the Features tab for more details. from SP on how to run different configurations of the organ with less memory..
See https://www.sonusparadisi.cz/en/organs/netherlands/rotterdam-laurenskerk-transept-organ-a.html and click on the Features tab for details of the requirements for the Transept organ: the full instrument at 24 bits uses about 30GB - it would run on a Windows system with 32GB of memory at 20-bit resolution..
Iain