OK, so yes, you’ll need to adapt the commands a bit. Start here:
https://wiki.nethserver.org/doku.php?id=howto:nextcloud
and here:
http://docs.nethserver.org/projects/nethserver-devel/en/v7/nethserver-nextcloud.html
Though I repeat that it would probably be better for you to just mount your storage disk at the right place, so no changes to Nextcloud itself are necessary. Moving the data could result in incompatibility with future releases (of Nextcloud or of Nethserver), and also probably means it won’t be backed up.