Answer:
In this case, it may help to download and install Bentley Synchronizer.
Check your RFEM 5 program version and download the necessary installation file.
For RFEM up to version 5.24, the Bentley Synchronizer version 10 is supported (Download 1).
As of RFEM 5.25, the Bentley Synchronizer version 11 is supported (Download 2).