Does Amazon print the shipping box label?

I was a seller on Amazon about one year ago, maybe a little more. I remember when I had to send my one box that had 4 units in it, I printed the barcode labels and I was able to have Amazon set up the actual shipping and print the label (the actual shipping label). Now I am stopped at the section where Amazon is asking me to put the tracking number in the box to set up tracking details. I chose UPS at first but Amazon said this was a (non-partnered carrier) so I saw the button “change carrier” and I switched to fedex, but I do not see a way for getting that tracking number. Am I supposed to leave the seller central totally and then get my own shipping label (like from Shippo for example) and then put the tracking number info in that box so I can proceed? Last time I was able to have Amazon walk me through setting up the shipping and printing that label… Can someone explain? The tutorial does not help.