Hi there,
Thank you for confirming that — you tested with WooCommerce and your custom child theme.
As mentioned though, issues like the one you were seeing are quite often caused by conflicts with code in custom themes.
In your last reply, do you mean that when you deactivate other plugins you are no longer able to see your products or add them to cart? If all of your products are a special product type coming from a different plugin, then that could cause issues. If that’s the case, then please test with just a simple product from the core WooCommerce plugin to see if that shows up.
I just took a look at the site again, and am no longer seeing the “spinning forever” issue on the “Place order” button. So that is a good sign. I’m unable to proceed without registering/logging in so, it’s hard to tell, but hopefully you’ve already resolved this.

Link to image: https://d.pr/i/DRcQS4
If you are still having issues though, please test with only WooCommerce and the default Storefront theme to see if that resolves the issue.