I'm going to assume you are on Mac, and maybe using Homebrew.
Whenever I need to have this plugin load in calibre I need to run this before launching:
Code:
brew unlink openssl@3
Then after quitting calibre:
Code:
brew link openssl@3
The unlink step should let you install directly in calibre.
It seems release version has issue with the current version of openssl, and has for some time now.
There is a beta version that's supposed to work with it, but I prefer the above workaround until the release version is fixed, as I do not want to run my Mac without latest version of openssl installed.
I do not know when that will be though I've asked on the DeACSM thread.
I only need to use the plugin 1 or 2 times a month, the rest of the time it fails to load in calibre but I don't need it to.