How to align add to cart button in DP Woo Product?

Use this CSS in your Divi Theme options to equal the height of the products in DP Products module:

.dipl_single_woo_product {
height: 100%;
display: flex;
flex-direction: column;
}

.dipl_single_woo_product_content {
display: flex;
flex-direction: column;
justify-content: space-between;
flex-grow: 1;
}

.dipl_woo_products_isotope_item {
background: #fff;
display: flex;
flex-direction: column;
}

.dipl_woo_products_layout {
display: flex !important;
flex-wrap: wrap;
}