Ghyslain, it seems I missed more than one step during the build of the plug-in 1.3. [:(]
Please try the version 1.3.2 which should fix at least the "Library not loaded" errors you reported. Not sure if the other errors are bound to this first ones. I hope so.

Does this version incorporate the new source code of YafaRay?

No, versions 1.3.1 and 1.3.2 fixes only wrong internal links in .dylib libraries for macOS. The recent changes in YafaRay will be incorporated to YafaRay rendering plug-in later. It's not urgent because the change log lists only issues on some features not used in the plug-in.

Can I somehow use it for video too?

See PhotoVideoRendering plug-in cited in plug-ins page.