You can find it in your profile page on the Aera by OneFootball website. Simply go here https://aera.onefootball.com/profile and login.
Your Dapper Wallet ID is the string of letters and numbers you can see at the top of your profile page. In the example below you can see where it is. The Dapper Wallet ID has also a copy button near it.
Please always add this information when sending a ticket to us related to technical errors on the Aera website.