I just had my first round interview at BCG (German office) and wanted to share my experience with the chatbot:
I had 20 minutes for 8 questions - in theory. The layout looks like a messenger on the phone, which means it is a narrow window in the middle of the screen. That makes it hard to read a long case description and find information later on. In my case, I had to scroll up and down all the time. The given data is like a sent picture, which means you can't open the picture and see the text (with the question) at the same time. Also, you can't type your answer while the picture is open.

To answer the question you're given some options and are told how many of them you have to choose (for example 5 out of 9). After that, the bot would ask you to explain your choice in 2-3 sentences. These two actions are considered as one question! If your answer is wrong (i.g. a numerical question or you've not chosen the desired strategy) the bot will ask you follow-up questions to lead you to the right answer. These actions also are considered the same one question. You can not skip a question or go back.

In the end, I had 60 seconds to prepare a recommendation and 60 seconds to record a video. I was supposed to have two attempts but that didn't work for me so I ended up with one take only.