This is just an informational message letting you know that on Linux EZproxy can only use ports below 1024 if it is run by root.
If you are hosted by OCLC you don't need to worry about this. OCLC ensures your system is configured and running properly.
If you are self-hosted and have issues getting EZproxy to run because of this, then you can find information on this in the LoginPort and LoginPortSSL pages, as well as the page about using the RunAs directive.