The resources part of the system is all about capturing information that is relevant to you or which you have an interest in. But it's not just about collecting - you have to actually use the content later on too.
This is essentially a collection of your knowledge and interests. Think of it like the bookmarks folder but way more organised and useful. It's not just limited to links, it can be stuff like:
It's your own mini-library of all the content you've consumed that you think is worthy of saving or something you might like to come back to someday and use on a future occasion. This is probably the most appealing part of the PAPER System to architecture students because there is so much information we need along with external assets and references that it can get quite confusing to keep track of them.
If you're looking for specific architecture resources head to the MAD Index, the largest collection of links, blogs, websites, social media pages and much more!
But the important part of the resources section is that it needs to be something you can actively see at all times. You might be inclined to save and forget about something which defeats the purpose of having the collection in the first place. A good way to begin is to set up a Resonance Box/Calendar which you can use with Notion's Web Clipper that will save any kind of resource, an article or a video and store it in your Notion.