I haven't yet launched my Shopify store, but am ready to - only problem is the checkout. When I test it I get the following message:
If anyone has any support they can give on this I'd be so grateful.
So the https://mamamoosclothing.com/ had switched to 'Dormant' plan for some time, which is a plan that keeps the Shopify admin available so the shop can still be built, but the checkout system will be disabled so customers won't be able to make any purchases. That would also result in the 'Checkout system disabled' error you saw.