By default, you get only the freshest 100/200/500 files/folders in RSS. If you want to get older files, you should use “Get old links from catalogue” feature.
Suppose you want to fill the site with files published during last 2 months, and you want this process to be finished in one week. Go to Catalog page, set the needed filters (category, language etc.), set “Links amount” to 500. Expand “Advanced settings”, mark “Get old links from catalogue” option, set the following options: Start date “60” days ago, Finishing in “7” days. System recommends you interval between fetching RSS: 25 minutes. Press “Save and search”, copy RSS feed address, link it to your site and set up files import from the feed for every 25 minutes.
Immediately after creation feed will contain files added 60 days ago. After 3 hours it will contain files added 59 days ago. And so on. Week later feed will contain only freshest files, and then the feed starts working just as usual feed.
Recommended RSS fetching interval is calculated in such way that all the files from requested period will get to RSS. If you don’t care if some files will not be imported – you can set the larger RSS fetching interval.