A small catalogue of downloads is easier to maintain when each file has an owner, a date and a clear purpose.
List the page where a download is linked, its filename and the version visitors should receive. Open each file and check whether it contains obsolete links, examples or references. Use a readable filename with a short version or date when updates matter.
When you replace a file, test the link from the public page and open the delivered version. Keep the previous copy in your project archive. Add a review date for material that depends on changing tools or information.