Orthotropic materials (and composite shells) are not yet available in PrePoMax and you would have to use the Keyword Editor to define them. Here’s the syntax for orthotropic elasticity:
*ELASTIC, TYPE=ENGINEERING CONSTANTS
E_1, E_2, E_3, v_12, v_13, v_23, G_12, G_13
G_23
You can find many examples on the forum. Such as: https://prepomax.discourse.group/t/orthotropic-aterial-support/143 and https://prepomax.discourse.group/t/structural-analysis-of-glulam/2255