@craig @jcasman
I think we solved the problem with the installer
installed the older version Ricoh Theta version 3.3.0
when it was running we got this message
leading to this webpage https://support.theta360.com/en/download/pcmac/
after downloading and installing this happens
RICOH THETA is running.
Click OK to close it.
after that the Ricoh Theta version 3.15.0
installed with no Problem
Conclusion: it seems that version Ricoh Theta version 3.3.0 has to be installed
and then upgraded to the latest Ricoh Theta version 3.15.0
hope this was helpful
Regards Svendus