Step by step guide for a complete beginner?

I finally received my first NAS, I was wondering if anyone has any recommendations of a true step by step guide in order to set it up properly. Current goals is for plex (home use and for family), and as a personal cloud storage.

I found Dr. Frankenstein's and Wundertech's guides. Anything else? I would prefer to just start with one guide, but browsing through both guides I found that Dr. Frankenstein's step 2 talks about setting up Docker UID and GID which is nowhere to be found in the whole setup by Wundertech. Again, I am a beginner so this just confuses me on what is important and what isn't.