Navigation with Lidar, Zed but no encoders on a custom 6 Wheels rover

edit

Hello, after reading and studying alot, i was able to connect all toghether. My hardware is this: Jetson TX1 Arduino mega connected to three L298N that drives 6x12V motors RPLidar Zed Mini I created the URDF and so on.... I setup everythings i tried with RTAB and GMAPPING but when i provide a goal it start moving (slow and after a while it hang). I don't have encoders on wheels i don't know if this might be the reason. Odometry is provided by ZED Mini Are Encoders a must? Any help will be much appreciate Fabio