XnView Software

I think my guide above could actually simplified slightly:

Extract the Power Retouch plug-ins download [to anywhere];

Run the x32 or x64 installer to install the plug-ins in the XnView MP plugins folder;

Restart XnView MP.

Then select a filter as usual from Image > Adobe Photoshop Plugin ...

XnViewMP installation is not equal to the Photoshop.
In MP it is: With an open image, menu Image, Adobe Photoshop Plugin (Ctrl + G) and in the window that opens press Setup, Add (here you select the folder with the plugins) and OK.
We return to the window Adobe Plugin and if we are in MPx32 will see ...

xnview wrote:is it a x64bits plugin?

With MPx32 is OK the 32-bit plugin.
With MPx64 not work either (64 or 32), simply does not load.

Conversely, (also in Windows 10x64) with MP-0.78x32 the plugin works perfectly.