I seriously wish you all the best of luck.
It is not easy - despite what people may have told you or what you believe. The toolset in itself is a tremendous restrictor of storytelling ability, players may test your patience on a regular basis, you will see sides of people you never knew existed and you will find yourself frustrated unless you plan hard and well. It also takes up a lot of time - far more than I had.
From a failed ADM, my only bit of advice is budget your time for DMing specifically. Get in, do what you need to, get out. Do not linger in the toolset. Tech support is something you allocate time for, not a full time job. Just do what you came to do and go. Oh and when the other DMs tell you not to bother reading a particular sub forum, LISTEN TO THEM.
Despite that, I enjoyed my time for the most part and even though virtually none of my plots got to see fruition on account of all of the above, it wasn't something I regret doing and it made me want to go and DM in real life. My 5e group that meets on Saturdays is entirely down to this place and I tell my players stories about what happened here, both good, bad and funny.
I hope to see you all in game on my rare visits
EDIT: Oh, one final bit of advice. The large movement blocker has almost exactly the same floor point size as one corner of the windmill and is almost exactly one and a half character widths across. It is also almost exactly the same size as the 6 foot object deletion circle.
You can use the latter as a guide for how much space you need to block off
