Hello Max, and thank you for posting to our community.
Normally your postage purchases from the Ready to Purchase page sent to both your Ready to Print and Shipment History pages for printing.
It's not clear why the labels did not appear in your Ready to Print page, however I do see them listed in your Shipment History page.
Those can be printed from Shipment History, using the step-by-step instructions in the link below.
Thank you and happy shipping!