I need to have a link to the download of the resource pack not only implemented in the server so my players could download it instead of loading it every single time

Check your server logs, the RP link for your server version will be there. If you don't see it use magic rpcheck on the console.

Also worth noting is that the latest builds have some new features that give you some choices as to how to serve your RP.

Players can choose how to get the rp with the getrp command, and use getrp url to get the URL if they want to download it themselves.