About the offline installation: yes I can see it in 5.1, you cannot? What do you see?
About the log files (thanks!):
The content of the create_env.err is unknown to me, maybe @carstenhaubold has seen that before:
./create_env.sh: line 54: ./micromamba: Bad CPU type in executable
The knime log says that PKIX path building failed
Could you try this fix? No, this fix assumes that you have access to the internet via a proxy. I would hope that following the offline installation path resolves the issue. Sorry for the inconveniences.
Best regards
Steffen