The Universal Apps are pre-built components, which you can work upon to achieve your integration’s goal. The LinkApi team has built a series of Apps considering which ones were the most consumed and asked by the community. If you don't find the App you want to use, consider creating a Private App. Also, our list of Apps are constantly growing, so you can always suggest an App to us.
There's two ways to use an Universal App inside LinkApi. In the Universal App list inside your Catalog, you can search for them and browse inside its configs to see if the App has all the Resources - Resources - Resources are a part of an Application. They're the treated endpoints to connect with. you need. If it doesn't, you can add new ones and make a clone of that App to your Private Catalog.
If the Resources listed for that App are what you need, you just need to list that App as a Dependency inside your Project, when your're creating or editing it.