When orders start coming through from Squarespace, they won’t automatically be fulfilled. The first order for every product variant will show up as an “unsynced product” under the newly created Squarespace store you connected with Printful.
To get that order through, you need to sync that variant and submit that first order manually. After the product is synced, any future orders for the same variant will go through automatically.
If you don’t want to import certain products to Printful, simply click on the order => “Confirm order” => “Ignore products”. If the variant is ignored, any future order with this variant will not be imported.