What size pool jets am I supposed to purchase for 1.5 inch pipes?
Nominal pipe size is for the hole on the inside of the pipe, and that is still subject to "nominal"

A pipe which is 1-1/2 inches (actually 1.557) on the outside is a 1-1/4" pipe.

A 1-1/2 inch pipe is 1.796 inches OD.

Here's a handy and very detailed chart/diagram

You have been asking for the wrong part, and have been sent the part you asked for, twice.