I agree that their marketing page could use a bit more "truth in advertising."
You can build a website with Bootstrap Studio without any coding knowledge, but it will be LIMITED. You really MUST learn CSS to get the most out of this program, if you want to be able to customize your websites so they look like anything other than boilerplate Bootstrap websites.
You MUST watch the tutorial videos (it helps to build along with them) to get some of the nuances of the program. Unfortunately, there are online courses for BSS. It would probably be a profitable course to create for beginners. I may even making one. There are a lot of features to this program that are not immediately apparent to new users and non-website-savvy people. You can always come to the forums to ask for help, but DO first watch the videos and read the tutorials thoroughly so you have a handle on the answer people give you. You should know your way around the BBS UI so that when people give you help, you know what they mean when they say, "Overview Panel", or "Options Panel", or "Styles Tab."
BSS is nothing like InDesign. InDesign is a page layout program that lets you put anything, anywhere. Bootstrap uses a grid-based layout system based on CSS flexbox (which you should definitely learn, there are many websites with good free flexbox tutorials like flexbox froggy (Google it)). Bootstrap also uses a hierarchy that sort of goes Section > Container > Row > Column(s). Columns contain components like headings, paragraphs, images, etc. Columns can also contain rows, so you can nest things and get some very sophisticated layouts. The responsiveness of Bootstrap is its biggest strength, and becoming familiar with how Column options are set at different breakpoints is a big part of mastering layout in Bootstrap. Also, responsive display is a big thing you need to learn (being able to hide/show certain things at certain sizes.)
Bootstrap also uses hundreds of "helper classes" which you want to familiarize yourself with, because they save a great deal of time. Adding helper classes through the attributes Panel is about 30% of building websites in BSS IMO. The official Bootstrap Website is mandatory reading. And you definitely need to learn how to write CSS, and not use "inline CSS rules." That's a big no-no in terms of best practices.
I think Wix is the worst thing to every happen to the internet since Flash.