I'm not sure what the "structure" is that they refer to but at GMATPill - we call it connecting the dots.
Each passage is written by someone, a real person. That person has something to say and usually they are writing with the purpose of communicating something. What is that purpose?
1) Inform the reader - general description of a topic
2) Describe a process and say why it's good (SUPPORT)
3) Describe a process and say why it needs to change (AGAINST)
4) Things used to be a certain way, now it's a new way (CHANGE)
etc...
Whatever the "story" is, you can find out by paying close attention to key transitive phrases (however, usually, although, etc) in areas of high probability (first sentence of each paragraph and second sentence connecting what rest of paragraph might say).
If you read only the "high probability" areas you can maybe label 3-4 dots in the passage. Connect the dots and backwards explain what the passage was about to yourself. You'll see that your comprehension level becomes much clearer.