If you don't have the 'Show on Map' button, you're connected to Garmin Explore! With this connection, you're not be able to display single tracks, only a collection of them via Garmin Explore!
You can either disconnect your Zumo XT from Explore or you must use the Explore app or the Explore website to put the needed track in one of your collections and then make this collection to be shown on the map! Both possibility's are well-documented in @jfheaths great 'manual' for the Zumo XT and his companion software Basecamp, Garmin Drive app and Garmin Explore. You can access it here: viewtopic.php?t=1464