Just be aware, there is a lot of lore. Over fifty years worth of lore. But you don't need to know all of it, in the same way that if you were running a modern day game set in Michigan you wouldn't need to know the history of South Korea or the mythology of Equatorial Guinea. Or even all the history of Michigan!

If you do decide to go forward with RQG, let me also recommend Six Seasons In Sartar available from DriveThruRPG. It starts player characters off in a small valley in the Dragon Pass area, just before their initiation into a cult. They're all from the same tribe, so they know and (hopefully) trust each other, and it expands from very small, cozy beginnings, through another two volumes, into active participation in world-changing events.