I have not investigated the "web link" feature in FTM, in the least, so I can't explain or understand the need or use at this time.
However, purely from a GEDCOM standpoint the following is how I might set up a source_citation to have a URL link and media in my DB.
2 DATE 17 MAY 2008
2 PLAC Windsor, Berkshire, England
2 ADDR St George’s Chapel, Windsor Castle
2 SOUR @S1@
3 PAGE https://en.wikipedia.org/wiki/Autumn_Phillips
3 OBJE @M30@
How does this translate to FTM?