Mine were both 0, but this may not be every case. I did this by going to the SSH add-on Web GUI and entering “id $user”. As the documentation says: Disable Protection Mode and restart it. Backup with a snaphot in HA and download it just in case. Here is what I did if anyone is trying the same: I had been mean meaning to investigate Portainer and now have a Calibre Web container working under it (pending some time to see if it’s stable). Recently the add on has been stuck in a boot loop on the latest HA version on my machine and I was not able to debug it. I use Calibre Web all the time running in Homeassistant on my Pi 2.
As a workaround I have mounted the share directory on my PC and use Rsync to mirror the two libraries so that when I add or read a book on one side it eventually matches up on the other side. Calibre on my PC won’t use the share directory as the main library as it sees the share directory as corrupt.
Within the admin section of the add-on you can update to the latest version of Calibre Web, although it will revert if you restart the Rpi. I have 20 GB of books on a 64GB SD card in an Rpi 2. This add-on is really the missing piece for my Hassio setup. When I entered /share/calibre (with a leading slash) it all worked fine. This did connect and gave me the listings, but no cover images or download capability.
When the Calibre Web addon (on the page hassio address”:8083 if you use port 8083) asks for the location of the Calibre library folder I entered the path as share/calibre (ie no leading slash using the share directory and a folder named calibre holding the books). When I was setting mine up I found a slight directory syntax issue.