Confused about UPC and company prefixes and starting out in general

Hi all, I just started getting into Amazon fba two monthd ago and am trying to get my first product listed. For some context I am starting as a sole proprietor without any business entity set up.

I have 3 variations so I meant to buy 3 UPC codes but ended up purchasing nonrefundable 10 company prefix barcodes which I realized aren’t the same as upc barcodes, I know stupid mistake.

So would I still need to buy UPCs or is there a way to convert these prefixes into UPC? Should I be using them to create UPCs? I feel like trying to use the prefixes will make things more complicated and I have nobody to ask so I came here to reddit lol

I have a manufacturer I am talking to and I just need to give them the packaging design w barcodes then I will make the first production order. I created an amazonseller account but I haven’t created a store or done anything on there yetshould i have done that before making a production order? What is the best sequence of steps for me to take from here?? Any advice would be appreciated thank you!