The app is called Play MGM. I believe you have to set up and activate the ability to use the account in person, so visit the sports book when you arrive and do it ahead of Thursday. The app has a geo function that only allows it to work within the state of Nevada so unfortunately you can't take the action with you when you leave.

You can download the app in advance from the app store. But you need to hand over cash at the sports book to fund your account. Then you can use the app to place bets.