Okay, the FAQ says
Community license keys are bundled in PGI download packages for versions designated a ‘Community Edition’ release. These are valid for one year from date of release, are not FlexNet managed and can be installed on any supported system type.
So FlexNet has nothing to do with this installation not working. Why is there a reference to ‘flexln’ in the PGI.BAT file? Hm.
Perhaps I should be assuming that it is reading the license file correctly?