Ok, got user and root, without m********t…
Some tipps&tricks:
Foothold:
Play around and google. There are different(!) ways to get in (don’t go for copy&paste exploits… won’t work :P), BUT as everyone is messing like stupid with automated tools (it is more efficient btw to do it manually…) the box is heavily stressed and flipping around.
As soon as you get in, try to automate it. You do not need some kind of vuln frameworks, a simple bash script is enough to get the low priv shell in. I had to repeat the execution of the script sometimes up to 15 minutes(yes, I used delays :D) until I got in again because ppl were messing with the box. So don’t give up ^^
user:
Now you’re inside, explore what you get. iterate through all files you can open, abuse them and use some basic Linux commands.
root:
my internet sucks, I wouldn’t be able to download bigger frameworks for automation in less than many hours…so back2roots.
Look what you get beside on other ports, get in and play around.
github + chrome/curl was enough to get root.
(now automated with few lines bash)
tldr:
use your brain, frameworks will fail.
“READONLY” and similar messages popping up because ppl try stuff, read the docs for the application to know how to help yourself or wait some minutes until the box had some (soft?) reset on that and is working again. It can be super annoying…I know
Write your findings into a script to have one command to get into in, as its annoying otherwise to execute over and over again the same.
Feedback:
It was my first box on HTB and it was quite funny. I learned here and there some stuff, mainly to be patient because many persons here are messing around with the box which lets it sometimes in a weird state for a couple of minutes. This was from time to time really frustrating ^^
But overall, thanks @TheCyberGeek for this box, I really enjoyed it overall 
(I tried to keep it vague but if it already too much spoiler pls lock the post :))