I tried to install omv-extras through the install script, however in the browser clicking on omv-extras settings leads to an error with the message "The property 'extras' does not exist in the model 'conf.system.omvextras'."
Upon looking at the install logs, there was actually an error: https://paste.ee/p/97Gs4
I found this other thread and ran omv-aptclean (which ran without error, but did not fix the issue), as well as the omv-confdbadm command with 5.3.6 replaced with my openmediavault and omv-extras version (I tried both). The omv-salt command produced the same error.
I'm running this on a raspberry pi with debian 10.