You don't have to do your personalization right away, you have time to do it before the start of the festival.
Any subsequent change of name is subject to a charge. It is therefore best not to personalize your ticket until you are sure who will use the ticket. All tickets in an order must be personalized together.
You can personalize it in your myticket account. There you can press "Print" for the ticket and then enter the name of the person who should be able to use the ticket. After that, the ticket will be generated and you can download it. This is also required for the extras, but it doesn't play a role there at the festival.
The ability to change personalization is expected to be available from early 2023.
All other tickets (tents, mobile toilets, etc.) are not personalized and do not have to be re-personalized if passed on.