Answer:
The current versions of RFEM and RSTAB are only available as 64-bit versions. We recommend using the 64-bit version of Windows. This should be possible without problems.
If you still want to use a 32-bit version of RFEM or RSTAB, you can download the previous versions using these two links:
http://extranet.dlubal.com/?file=RSTAB8.07.11_32bit.exe