To proceed to payment you'll need to make sure that your web browser allow pop-ups and redirects from https://retail.sytravelmaster.com.
To resolve this for an android device please work through the following solution.
From an Android device:
Go to the website settings on your device:
Go to site settings:
Go to all sites:
Select pop-ups and redirects:
Check that your site settings allows pop-ups and redirects on your device:
Return to https://retail.sytravelmaster.com proceed to payment.