That means after you (or your agent) submit for an audition, casting can request an ECO Cast and give you a deadline to submit it by and some details for your audition. You would receive this ECO Cast request through Actors Access and you would upload and submit your video there as well.
Can I wear jeans to an audition?
You don’t need to dress like you’re going in for a corporate interview here. Your clothes shouldn’t be a wrinkled mess, but you also shouldn’t be wearing business attire to an audition. A good pair of jeans can go a long way, and it’s worth investing in a pair for auditions alone.