When joining a new software team, what are some good initial questions I should ask to begin understanding the stack? [closed]

I just joined my first software team and I have no idea how the product/files are structured. There are thousands of files under hundreds of directories that we are responsible for. It’s mainly Angular, C#/.NET, and SQL based, using both Azure and AWS for different dependency niches. It is not feasible to read through every file to understand it, but I haven’t been given any documentation or good commenting/READMEs. How can I best probe my team to understand what’s going on?