You already have your solution. You typed it out.

You ask questions. You stop them and circle back to the overview and context. Ask them about the high level. Ask them for the pretty pictures PPT.

If they deviate from what you need, stop them politely and put them back on track with the excuse of "it will help me understand this better so I can provide a solution".

I am one of those people that is very bad at explaining. Please let me know if you have any additional resources for explaining things better.