He does not support the ramps boards anymore (never really did). I wouldn’t get to comfortable with it as the new versions do not include it at all. so you are starting with outdated software…not a good idea.
As for your problem I have the steps required and the other jumper changes needed linked in the estlcam beta link, I have the second post.
Just stick with the way the majority of us do it and the way I recommend.
Short update on this topic as I have found it often while looking for a way to use ESTLCAM with Ramps 1.4.
It works with the current version 11.228! Reflashing the firmware is way faster than putting Marlin onto the Atmega 2560.
The big benefit with using ESTLCAM is that moving the Lowrider is waaaay more convenient than with Repetier Host as it moves stepless (Diagonal etc… is just awesome). Means it only moves as long as you press a button. With Repetier Host or with the LCD display I often moved too far and had to hit the reset button, resulting in droping the machine (Yep, Lowrider is a heavy beast ).
I will continue to use Repetier Host as a visualizer for the GCode to check if the cnc-paths are good. But navigating the machine? ESTLCAM it is