ClassicPress Plugin for Featured Image from URL

[EliteStarServices]

@viktor

Many plugins set the minimum version to 5+ simply to avoid offering support for lower versions even if plugins work. Some functions were backported from WordPress 5+ to ClassicPress. I use Plugin Doctor - WPSeek.com to check plugins/themes for the minimum version based on the core functions used. When v2.0 drops, more plugins will work.

This helped me, you may need to edit the plugin to say 4.9 so it will install.