No products to add to cart

First, make sure you have created some products with prices and assigned them to at least one category. Products that are not assigned to any category will not appear as an option to be purchased. Even if you do not need to use multiple categories, there should be at least one default category that all products get assigned to.

The other reason is that you have enabled proofing either for the specific gallery or in the general settings. Go to Sunshine > Settings > Galleries > Proofing to see if this is enabled. You can also edit the respective gallery and find the Proofing option. If Proofing is enabled, all add to cart and checkout features are disabled which is why you are not seeing any of these features.