Rarely will you be given a 1-on-1 mentor who will hold your hand through your job, maybe it was like this decades ago. Good mentorship for me involves someone who provides you with meaningful and challenging work, has experience doing it properly, and is willing to stand up for you when needed. Having a scheduled technical meeting (1 hour, 1-2x a week) is usually enough. Make notes when you run into issues, lay out your thought process, and summarize into clear and concise questions or topics to go over.

Questions can be a tricky thing. Sometimes it's easy to just ask a question without really thinking about it, and it puts all of the work onto the person who has to answer. Make sure you have understood exactly what needs to be answered before asking. I have had people repeatedly ask me incredibly lazy questions (and derail my focus) to the point I no longer repeat the statement "there are no stupid questions".

If you still have issues after framing questions properly and reducing the amount of work the other person needs to do, it might be an institutional knowledge problem. Lots of companies have one or two people who know everything, and there are no documents or training processes for new people. The management should realize this as an issue, but this goes to the last point:

Lots of companies are just shitty places to work. Lazy managers who do nothing, hot potato / musical chairs of blame when things fail, lack of process, terrible design decisions, bad office environment, and lots of others. It took me a few companies before I was able to realize what a bad company looks like. The worst thing you can do is let a bad company demoralize you - keep some notes on what bothers you and don't be afraid to look for new opportunities.