Archiving backup files confusion

I am new to this Ubuntu thing and I am having troubles figuring out how to copy the backup directory to the second drive in my System76 Meerkat server. I attempted to use the Files app; tried dragging the 'home/user-data/backup/encrypted/ directory over to the newly created directory “archive_20200428”. No go. Complained that "error while copying “duplicity-******.sigtar.ggg. Permission Denied”. It makes the same complaint for every file in the encrypted directory.

Would someone be willing to hold my hand a bit by giving me more specific instructions rather than the simple ‘backup to second drive’?


So I was able to do it using the Terminal
sudo cp -r /home/user-data/backup/encrypted /media/otherdrive/archive__20200428/

I am happy to have it copied.
But I would still love an explanation as to why I am unable to do it using the Files app.

Is my next step of automation to create a cronjob? Or is there a smarter way to do this with MiaB?
Or is this where I should use rsync? If so, can you give me a sample command to set that up?

Thanks for any guidance,