Unless the event specifically states that non-personalized orders will be canceled, there is no need to worry!
Ideally, it is always best to personalize your tickets within the deadlines sent to you from the event organization.
If you missed the deadline, the tickets will be sent to you by email. You can download and use these tickets. As the tickets are not personalized, please make sure that you go to the event together with all the people that use one of your tickets. You as the main buyer have to be present with the others, and every ticket holder must have a valid ID card.
Note: Personalization is designed to prevent resale by third parties. Since personalization is active for this event it is possible that you might be checked for ID at the entrance. In case of unpersonalized tickets, entry can be refused if the main buyer is not present.