I know this is an old post but I figured I’d update it in case others are are googling the answer like I was.
The offset is the starting point of the request. So if you want to retrieve 5 items at a time you’d use limit=5&offset=0 to retrieve items 0-4 and then limit=5&offset=5 to retrieve items 5-9.
I worked around the rate limit by setting up a reverse proxy to the webflow API which caches results so that repeat requests are served from the proxies cache rather than hitting the webflow API. Unfortunately you’re still limited to 6000 results per minute.