How to add squaretrade protection on wining bid

[boosoon0]

I won a bid for a Canon EOS M50 Mirrorless Digital Camera but i dont see my square trade protection plan in my check out.  I still bought the camera but I would still like the protection plan.  What do I do?  The item # is 156218637319

[krazzykats]

 Allstate Protection Plans (squaretrade.com)