This is the password for your computer to allow the program access to run. Once you put this in the program loads and you run through a few steps to flash the sd card. Could I suggest you make sure you download the 0.40 rc4 version of rasplex from GitHub and use this, the default options on the installer are a little out of date. I would also suggest a USB3 install if finance allows together with an overclock. Search for dlanor’s method in this forum. Works well for me.
I was using a Mac mini core 2 duo 2 GHz as the server and player and was expeirencing a lot of stuttering/frame dropping with 1080p high bit rate dts movies so I decided to try the Raspberry Pi with RasPlex.
I am still using the Mac mini as the server.
Rasplex has eliminated almost all the stuttering/drops ( only one instance so far). I am also using Dianor's settings.