How to start encrypt external drive on MacBook?!

Hello, since I can’t backup my hard drive using CCC to an encrypted drive, I created my external drive as APFS. I backed up, and I want to encrypt the external drive to protect it. Don’t have a context menu item “encrypt” in finder, so I want to use terminal to get to it, but not sure how to start it. “sudodiskutilapfsencryptvolume disk8s5 -user maik” - ‘You must specify the Disk user when starting encryption with no existing users’. What does it mean?

Hey there!
Check the information in this link
There is the solution for mac and windows