That's OK and expected. ADE will only display options for the sims that are installed. You would need P3D v4 installed to actually compile for that version. However if you open ADE for FSX you can create an airport and compile it for FSX. The bgl files created need to be added to the P3D v4 installation and then, if there is nothing unexpected, the user should see a working airport
If it works all well and good. If not then you can send me the FSX project and I will recompile it for P3D v4.5