"fv20" is likely the title or a shortcode assigned by the author.
In the Telegra.ph system, URLs are typically generated based on the title of the post followed by the date of creation. A URL ending in fv20-03-15 suggests: download https //telegra.ph/fv20-03-15
Technically, Telegra.ph is a webpage hosting service, not a direct file-download server. When users look to "download" from a Telegraph link, they are usually trying to retrieve the media or information contained within the post. "fv20" is likely the title or a shortcode