One thing you should definitely check in the device crossbar is whether it's taking video input from the yellow composite connector or the S-Video connector. I'm not too familiar with the EZCap but on all other USB capture devices I've used you have to select one or the other.

If using OBS studio, right-click on the device in your list of sources, then go to "Properties." Then click on the "Configure Crossbar" button and make sure in the drop-down menu the proper video input is selected.