From your screen shot, shouldn't 'enable updates deployment' be checked ... default is off - not checked.
It does say that for that to work the web service user needs to be able to write to the moodle code directories.
Then, In the listing of plugins that need updating then, there would be an 'install' button under each of those needing updating. You don't see the 'update database' until your moodle has acquired tne new code for at least one of those plugins.
'spirit of sharing', Ken