The password of the of Owncloud client is not saved and the user is prompted to enter its owncloud password at each opening of the session.
The message "No keychain service available" is displayed.
It seems there is no correct integration of the owncloud client with the gome-keyring system (Seahorse) in Gnome 3...
The gnomekeyring package is missing :
Close the session, reopen it and enter for the last time the password. It should now be saved in Seahorse correctly.