I highly appreciate that you try to transform Scrapbook into a WebExtension. I have tons of data in Scrapbook X and followed all the instructions to install, migrate and capture, but in the current stage this is pure rocket science to install and use.
I am stuck with the data in my Download folder, can't capture, have no sidebar to display and search my data and I have no idea how to get any functionality from it, so I give up. If there's a small chance to re-enable the usability of Scrapbook X you should go this way.

Note: My one star rating is not at all meant to discourage you but to reflect the current stage of usability. Of course this will be changed when the usability rises. Thanks for your work!