1. Make sure you have one or both of the pet dlcs.
2. Click subscribe.
3. Launch the game as modded.
4. Click mod list on the right side of the main menu.
5 Enable the mod and confirm.

That't all there is to it, any comments on the main page will be deleted unless they are dog or pokemon memes. Post here if you need help and please post more than just "it doesn't work".