This looks like an older version of the PlayOnline Viewer (what is its version string?), though I'm unsure why it wouldn't have updated before this part (I never tried installing via Steam though, in case it makes a difference).

You should not be able to actually log in with just the PlayOnline credentials (does it ask to update if you try to?).

Could also try to check for issues via the PlayOnline Viewer itself (maybe that triggers the update?).