I am unable to buy anything. It tells me something went wrong on our end. Please try again.?

This may depend on where the problem lies. Payments will be processed by your app store / google play store etc. The game may be having trouble communicating with them in which case the game developers need to resolve this. Or the app store may be having trouble charging your account. You could check that your account is in order with your app store. If it continues then check with the developers if there is a problem which they can fix. Check the support page for the contact details for the developers.