Does Extension Relationship Permissions as ACLs work on CiviCRM 5.2.3?
Email from the author says:

"Yes - it should work on the latest 5.x release. I'll remove the reference to 4.7 as 5.3 was a security release &amp; &lt; 5.3 is not secure.
I merged changes recently that probably mean the current version needs 5.4+ - I'd have to check."