[any ANONYMOUS forum user]

I think you folks are over-engineering this, especially if you use calibre.

Do this:
1. Download the full .7z archive and unpack the contents. You'll get a bunch of directories, including one called "Calibre_Plugins"
2. Go in the "Calibre_Plugins" directory and you will see a bunch of zip files, with a companion read me file for each.
3. Now go into Calibre and go into Preferences and then Plugins.
4. Click on "Load plugin from file" and navigate to the "Calibre_Plugins" directory that was created in Step 1 and select a plugin, accepted the buttons as they come.
5. Repeat step 4 for all the plugins you want to load.
6. Expand the "File type plugins" in Calibre (same location as step 3) and you will see each of the plugins you just loaded.
7. Click on a plugin and select the "Customize plugin" button at the bottom and do whatever was indicated for that plugin via the readme file in step 2.
8. Now you can use Calibre and import your DRM protected book.
9. Select your DRM protected book and use Calibre to "Convert" it - you can select the same format if you like (ie epub [ebook] to epub) and let it run.
10. When the conversion finishes, your old ebook will be renamed to a new "original_epub" and you'll have a new epub also, which will be unprotected.

Pretty simple, actually...