Office Store - can't buy or download add-ons

Hi,

I cannot seem to use the Office store to download add-ons. The 'Free Trial' or 'Buy' buttons are popping a new pop-up window like they should, but then when you try to click on the 'Continue' button in the pop-up nothing happens. See picture attached.

I have tried with multiple computers, using different browsers (Edge, Chrome, IE), and also in regular and inPrivate/incognito mode.

Even trying to add from the Sharpoint site itself (setting wheel -> add app) doesnt work, unless I am using specifically IE! If using Chrome or Edge, setting wheel -> add app does not work...  

Anyone seen this before or knows how to address this problem?