Passbolt container runs as specific user with a UID and GUID of 33.
Therefore, ensure proper permissions on the Docker data bind mount volumes:
sudo chgrp 33 /mnt/docker-volumes/passbolt/gpg
sudo chmod 770 /mnt/docker-volumes/passbolt/gpg
sudo chgrp 33 /mnt/docker-volumes/passbolt/jwt
sudo chmod 770 /mnt/docker-volumes/passbolt/jwt
After spawning up the container, you have to create your user account first. Please follow the referenced link above, which leads you to the official documentation and how-tos. It is also recommended to add SMTP into the mix to retrieve important emails.