Thanks for that info.
Here are the official Collabora instructions:
Mind following those steps instead?
I did a quick look comparing to the Linode article, and I see Linode had a few different commands. (Perhaps it was based on a slightly older version of COOL?)
Hmmmm… last year, there was someone who had the same exact error message as you.
In March, @switit gave an answer:
That might solve your issue.