Hi George,
EOS can do delegated xrootd TPC transfers and indeed it needs a XRootD proxy service in front that will handle the traffic. The EOS_FST_NO_SSS_ENFORCEMENT=1 is not needed in case you use the proxy service in front. This env can be used for instances that you control (both source and destination) but is not a recommended way for doing TPC with external sites.
All the steps to set this up are already laid out in the link that you pasted.
Cheers,
Elvin