If your tickets don't get printed properly, you can still enter the stadium by showing the PDF via your mobile phone. If you are going to print it anyway, proceed in one of the two following ways:
If you downloaded the PDF before printing, there is no problem. You can reprint the ticket once you've sorted out the technical issue.
If you did not save the file, you must go to the club ticket office to explain what has happened and after the corresponding verifications, and if applicable, a duplicate of the ticket will be made.