There are two main reasons we see the Add to Cart button may not be working on your product page after embedding the calculator:
Additional variants on the product page
Shopify theme having unusual code
The great thing is - we are usually able to resolve this by:
First, try removing any variant on the Shopify product.
If the calculator still doesn't show up then there will be some customization needed. Please email us at [email protected] with the URL to the product page and we will try to resolve this for you.