RaspberryMatic Openhab org.xml.sax.SAXException: Unknown XML-RPC tag: title

I wanted to use RaspberryMatic for HM and HM-IP instead of homegear.
This is my environment
RaspberryMatic 3.75.6 (rpi3)
Openhab 4.1.2 on a different rpi4
Homematic Binding 4.1.2
Fritzbox: 7590

An old rpi3 was used to install RaspberryMatic. Installation was fine boot.log is not showing any error.

Only Homematic addon binding fails. Autodiscovery works.
Firewall settings have been openend for testing. Authentication was disabled. Re-Direct to HTTP was activated.
Currently no RF module is installed on the RaspberryMatic RPI, but this should be an issue I believe.

I’ve found so many community articles but most were referring to the Firewall settings. I believe I can’t open it more.
Might there be settings on the Fritzbox Router required? Currently I have no clue why it fails.

Thanks for your support.

Once installed RPI-RF-MOD module raspberrymatic starts as expected and WebUI is available.