Can't access VM's after reinstall Fusion 8.5.10 Pro

I took the hard drive from my early 2009 iMac running High Sierra and added it as an external disc to my newer late 2013 iMac running Catalina.

I installed Fusion 8.5 and updates.

I can see all the files and VM's in Finder but I cannot import any VM'S. When I click on the VM to open it I get an error "Could not open /dev/vmmon: no such file or directory" followed by "Failed to initialise monitor device".

The OS and Fusion are new clean installs.

Any help (urgently) appreciated.