You can tell ANSYS to mesh with linear elements, and not quadratic. I think that is what you want. A rectangular shell element will have a bilinear shape function.
Click on the Mesh title in the outline in Mechanical. In the Defaults portion is Element Order which can be set to Linear.
After you solve, if you let ANSYS automatically select an element for you, you can see what element was used and what Keyops were used by searching through the solver output file.
There are ways to make ANSYS use a different element type or different Keyops, but is this sufficient for now?
I have attached an ANSYS 18.2 archive that you can open in 19.