Hi Towdy. Welcome to our community.
I think there is a misunderstanding here.
That installer option in File menu is for plugins and patches - Wings3D code.
Wings3D already comes with the Yafaray plugin installed.
The Yafaray installer you got from the official website should be installed as usual. I saw the latest version is available in .zip version. So, you just need to unpack the Yafaray files somewhere. The unpacked directory is named yafaray_v3.
Then, you must to tell Wings3D where to find the yafaray-xml.exe (assuming you are using Windows). You do that in the menu Edit->Plug-in Preferences->Yafaray....
In the shown dialog, you must to inform the fields: Executable and Yafaray Plugin Path (usually something like "C:\yafaray_v3\bin\yafaray-xml.exe" and "C:\yafaray_v3\bin\yafaray-plugins", respectively) - use the Browse buttons.
After that, you should be able to access the Yafaray options in Material and Light dialog as well as the Render->Yafaray... on the menu File option.
Just in case...
There is two thread related to Yafaray where you can get some information as well as ask too: Yafaray plugin and YafaRay Rendering Software
Let me know if you still have any problem to get it working.
I think there is a misunderstanding here.
That installer option in File menu is for plugins and patches - Wings3D code.
Wings3D already comes with the Yafaray plugin installed.
The Yafaray installer you got from the official website should be installed as usual. I saw the latest version is available in .zip version. So, you just need to unpack the Yafaray files somewhere. The unpacked directory is named yafaray_v3.
Then, you must to tell Wings3D where to find the yafaray-xml.exe (assuming you are using Windows). You do that in the menu Edit->Plug-in Preferences->Yafaray....
In the shown dialog, you must to inform the fields: Executable and Yafaray Plugin Path (usually something like "C:\yafaray_v3\bin\yafaray-xml.exe" and "C:\yafaray_v3\bin\yafaray-plugins", respectively) - use the Browse buttons.
After that, you should be able to access the Yafaray options in Material and Light dialog as well as the Render->Yafaray... on the menu File option.
Just in case...
There is two thread related to Yafaray where you can get some information as well as ask too: Yafaray plugin and YafaRay Rendering Software
Let me know if you still have any problem to get it working.