My Python Console does not show any Extension Pack Message
Is all you are seeing in your python console something like this (2 lines) ? Then read on.
1. Confirm in your Scripts Directory a file called ___initExtensionPack___.py exists.
2. Confirm in your Scripts Directory a folder called MariExtensionPack_5 exists
3. Confirm the Folder Structure within the MariExtensionPack_5 Folder looks like this (Resources,Shaders,Tools)
It is possible that your MARI Installation assumes a different Script Directory by default
1. Open your Python Console
2. In the lower section paste the following command: print(mari.resources.path(mari.resources.USER_SCRIPTS))
3. Hit the 'Evaluate' Button
4. Confirm the printed path is the path where Extension Pack is installed (see Solution 1)