You can contact your insurance company and see how they do it. Mine gave me a few websites that they work with. I used edgepark.com and got my pump in 2 days
I called my insurance company and they gave me a website with a purchase code and I picked out the one I wanted and they shipped it to me.
call your insurance company, mine actually reached out to me because of the confirmed test, the rep told me that once I was 8 months to request a breast pump and my obgyn will write a prescription and they will either shipped it to me or I can go to their pharmacy to get it. It's a madela pump in style advance double pump