Try this link to the official Musei Vaticani site. Unfortunately, if they are sold out they are sold out: https://m.museivaticani.va/content/museivaticani-mobile/it.html
Try this link to the official Musei Vaticani site. Unfortunately, if they are sold out they are sold out:
https://m.museivaticani.va/content/museivaticani-mobile/it.html
I‘m currently here and the waiting line for customers without a preorder ticket isn‘t that bad.