Just to be clear, you are using
this link on the POL frontpage to download/install the client? YES
Are you unable to enter the version update process after logging in? <YES This is normally where "missing dats" would get fixed or added. Actually.... In the screenshot you posted, it looks like FFXI is not installed at all. You should have an entry in that dropdown menu for Final Fantasy XI as well as POL and TM.
My advice is to clean out everything you have installed right now, then grab the client install from the POL link above and install properly. Make sure you scrub the registry after uninstall to be safe, and don't try using old archived installs. It's just not worth it given how often they get FUBAR'd.