The order process goes into multiple steps with several parties. Each step may fail and then the customer is frustrated.
In the order process MBS website sends you to the store website. If that website loads, you can enter your details. Then you get directed to the payment processor website (adyen or PayPal for example). These pages need to load and then loads itself the bank website for the second factor. Most banks ask you some additional thing like a token sent via SMS, a code generated in an app or a transaction password. Once that step is done, the bank redirects back to the shop and once you completed there, we get redirected to our website.
On that way of redirects, all content filters in the browser may decide to block something. But bigger problems seem to be that older browsers are in use and the latest TLS v1.2 is not used or not used with stronger cryptography.
If you run into those problems, please switch to a different browser, e.g. try a recently updated copy of Safari, Google Chrome or Firefox. You may disable ad blockers and make sure they are up to date including your operation system.