How to connect PSU to these PCB pads
You are indeed meant to solder your connector pigtail wires to those pads. If you prefer to use clip leads, standard 0.025" square pin headers will fit. And in this context fully assembled and tested refers to the Evaluation Kit board itself, we can't know what connector you will use, if any. We use a custom test fixture with spring-loaded "pogo pins" to contact those pads from below. This approach lets you eliminate contact resistance or use whichever connector you want. (I am one of the EV kit designers at Maxim Integrated... although I'm not the designer of the MAX14830EVKIT, I have designed many similar EV kits.)