I downloaded what appears to be a valid Photoshop "Extension". But install instructions saw to install with Extension Manager which is now RIP. It also say I can use Terminal App -which I'm not conversant in. Below are the instructions in the Install PDF:
Perhaps this app has not been optimized for Photoshop 2018, and is incompatible. I have installed Plugins without issue, but have not encountered "Extensions" for some time. Anyone here using this app? Any suggestions for install? (Obviously I'm not an IT wiz)
From the Install PDF:
Launch Terminal and run this command to open the install folder
(or open the folder by yourself):
Navigate to your download folder > 01_installation and copy the
folder “3D_Map_Generator_Terrain” into the extensions folder.
Restart Photoshop. You will find the extension in the Photoshop menu:
From which market you got extension? Adobe Exchange? Look at help file for contact email and ask developer. Name of the extension sounds familiar to me so it is possible that the developer posted the same extension on some other market so you can try to reach him elsewhere if contact email is not provided.