We don't have an option to directly create a 5 axis robot. However, you can create a 6 axis robot and put the 5th and 6th axis at a distance of 0 mm and then limit the rotation of the 6th axis to 0 degree. In other words, you just ignore the 6th axis.
That should do the trick. (Btw I never tried it, I'm just telling you what I would try.)
At the moment, it's totally normal. The way you built the robot, it's impossible for RoboDK to calculate the Inverse Kinematic of the robot. I really don't understand what you did with your axes 4, but it's not cutting it mathematically speaking.
Did you try what I suggested you with the axes 5 and 6?
I have an educational license with the name of Universidad Autonoma de Nuevo Leon. The robot is for academic use only. I plan to use robodk to program the Scorbot ER-IX robot in the robotic laboratory.