Lightroom expects all plug-ins to have a folder extension of “.lrplugin” or “.lrdevplugin”.
Please check what is the extension of the Plugin you are trying to load into the Lightroom.
The screenshot clearly shows that the plugin path ends with ".lrplugin", so that's not the issue. Two things to check:
1. In the error window, click OK. Then close and re-open the File > Plug-in Manager window. Sleect Aurora HDR Pro. Expand Plug-inAuthor Tools on the right by clicking on the arrow. Are there any diagnostic messages being displayed? Show a screenshot if so.
2. Double-check that you've actually placed the plugin at that location and that it is readable. To do that, in the Plug-in Manager window, click Show In Finder. Then in the finder, right-click AuroraHDRExport.lrplugin and do Show Package Contents. You should then see a number of files listed, especially including Info.lua.
Thank you both for trying to help me.
Unfortunately your suggestion didn't work but I kept trying and eventually found the answer to be:
Right click on the selected photo/s
Choose EXPORT TO AURORA HDR PRO