The most common reason to integrate is to put your own live data on a screen. A Salesforce dashboard, a finance board, a logistics view: these already exist in your tools, and you want them on the wall.
Most of that data sits behind a login, and a board of internal figures is not something to leave open on a public link. This is what the secure-access integrations are for. Through a built-in OAuth connection to a tool like Salesforce, you grant Screenly access to your data on your own terms: scoped to what it needs, and revocable whenever you choose, rather than handed a shared password or an open URL.
With that access in place, a screen can show what sits behind the login, and the data keeps itself current. Your figures reach the wall while you keep full control of who, and what, can reach them.