To see Instagram content on your UPshow screens, you must use an Instagram For Business account and your Instagram account must be connected to a Facebook Business Page. This a requirement from Instagram (which Facebook owns).
If you are still running into problems connecting your accounts, here's the basic troubleshooting steps to follow:
3. Make sure you are an Admin of the Facebook Page you connected to (This especially important if you didn't create your company's Facebook Page)
4. Once everything's set, add your Instagram Business Account to UPshow