You can install both if you want, though the one that gives pets through an image is the one you probably need for what you want to do.
Then you'd edit the 'get' page so that a user needs an item to access it. And upon either clicking the pet or visiting the page the item would be consumed.
If you want lots of adopts and they all have a different item, or you don't want to have multiple adopts on the same page, you can rename the 'get' page to the adopt name and have multiple, each for whatever adopts you want. Though make sure to follow all the steps once first so you can bug fix if needed.
I recommend reading through the post just to see how it all fits together as I can't explain that well