Hi,
when you get stuck in getting your Commandline Render app licensed in R21:
You can either do it the manual way by just alling them, or better, follow this articles to automatically use the license servers:
Maxon License server:
Detect Maxon License Server
RLM for Cinema 4D Commandline Render:
https://support.maxon.net/kb/faq.php?id=62
I hope this helps.
Andy