This is perfectly normal and is a security measure to prevent the sale of fake tickes.

Screenshots of your mobile ticket won't be accepted. 

You simply show the ticket on your phone when you arrive at the venue!

There is sometimes a small fee charged for mobile tickets. This is to help towards the costs of the scanning equipment and the staff scanning the tickets on the night!

Mobile tickets will be available to download a lot nearer the time of the event. This is to avoid the resale of tickets through online touts.

You will be notified via email when they are ready to download!