Not sure if you tried this version? I think this one should recognize your elicenser? https://helpcenter.steinberg.de/hc/en-us/articles/115000075750-Converting-Cubase-VST-songs-ALL-ARR-into-CPR-format
But then again… Some 5 years back I converted a few dozen*.arr’s in SX3 to *.cpr’s and I notice that that all the ones originally created on PC played fine in the latest version of Cubase. But all arr’s originally created on Atari had no data in the parts. That’s when I found out that you first need to open and save them in Cubase VST32 (the last version to support the arr & all formats) and then you can convert them in SX3 or SE3. Hope they can help you with this?