The add-on fields need to be positioned within the WooCommerce add to cart form on the product page. This is so their values can be captured when a user adds the product to the cart.
By default, they’re positioned before the add to cart button. However, you can move them to below the add to cart button using this snippet:
You can find out how to add a snippet here.
Moving the fields elsewhere on the page
The add-on fields are part of the WooCommerce cart form on the product page. These means that the data from the fields can be passed to WooCommerce when the user adds the product to the cart.
For this reason, it’s not easily possible to move the fields elsewhere on the product page.