Where to start?
The company has potential and (if they're still even there) some really smart, kind people. The issue is the boss, who can't focus on a single topic or see a single project to completion, yet wants to be involved in all projects and decisions. Worse yet, he goes nuts when things don't work out and will blame you, rather than his inability to remember what you or even he said even as recently as last week. This means that projects are regularly dismantled (often with a lot of screaming), to be replaced with "new" projects, which are actually the projects that got dismantled the cycle before last. Yes, the cycle repeats itself regularly.
If you were hoping someone might give you help in how to navigate this situation, especially when you're new, don't look to the "leaders". It's filled with people (like the writer of this company's only glowing, positive review), who will just repeat the same 10 or 15 lines they've been trained to by the boss, or by cowards who just want to interact with the boss as little as possible (and will also repeat the same lines, but do it with an angry face). Of course, this is because it's a "flat company" and there are no "leaders"! Silly me.
Are you not a developer? Did they tell you that you would be put in an area that interests you? Instead expect to be told to learn a topic you've likely never heard of, either alone or with someone else as equally unsure, and then present it to the boss a week later, after meetings with him for hours a day, usually stretching into overtime, in the way he likes. What is the way he likes? Reread the above. If you ask for more time, you will be told you have no "urgency", and asked if you are serious about working.
Oh, you're a developer? Expect the same. Then expect to have to reproduce the concept in whatever buzzword graphical format the boss recently read in a magazine, usually involving an obscene amount of bubbles, lines, or squares-nested-in-squares-nest-in-squares. Also expect no help from the dev leads, as they've made their careers out of doing as little new dev work as possible, either content to claim past dev's work as their own, or focusing on the company's oldest, most bug-ridden systems.
Ok, so now you've failed, as everyone does, because no one knows what the boss wants. Even the boss doesn't know what he wants.
If you're not a dev, maybe they promised a chance to learn an area you're interest in? Just kidding, you'll be sent to a floor to learn whatever process is shorthanded.
If you are a dev, you'll be put on fixing bugs from the old system, or trying to support the series of patchwork systems past devs secretly made, but then got adopted because they actually helped the company. Good luck, it's a mess. Have fun looking through a database with duplicated information everywhere, and tables you'll use most all named with abbreviations that there's an actual (incomplete) dictionary for.
If you work at HTM, this is your life. Get a project, fail, get yelled at, be put on normal work, boss forgets he hated you and puts you on a new project, repeat. If you manage to get hired and the boss internalizes he doesn't like you, congrats, as you now have a pretty easy job (outside the constant microaggressions from the boss and "leaders"), despite what the positive review says.
Or you can close the tab you have HTM's website open on and move on with your life, saving yourself from wasting, on average, 2-4 years of your life.