In my case i simply log in as admin, go to settings. Then there is a menu at the left side. Under the big point “Administration” klick on Overview. A few infos should then appear, one of them is your version together with a button for the upgrade.
key info missing from the docs was that the updater is under of the Overview menu on the left (maybe this was an old change at some point to the menu?).
NB this is not a term I would use or expect to find the function under. I would expect a separate “Update” menu item (as found in almost all other software I have ever used in the past 2 decades). In any case, could someone update the docs to add the following clarification:
From Admin user menu on the top right, select “Settings”
Then from the left hand menu, under Administration select “Overview” from there the Version information shows available upgrades.