You’ll likely find more configuration options if you open the configuration.h file. The Rumba Pins are already mapped, so default pins should work fine. To test. Disconnect your AC power and run a MM in diode mode across the AC output. It should give a scratchy beep when the PWM fires up. It will start at max PWM and slow as it reaches and maintains target temperature. Turning everything on, you should fine a new icon for heated bed on your LCD. Before testing the SSR, make sure it’s monitoring properly.