As we don't really know how the discord activation works for patrons (since we were already in the server prior to setting up patreon) its difficult for me to really advise you as to how to get it working.
It would be best for you to contact patreon support to assist you.
With that said, speaking with some of our current patrons it seems that sometimes connecting to the server doesn't work if you already have a pre-existing discord account and you attempt to connect it after making your pledge. The server should just appear in your server list after connecting on patreon, there is no invite link or anything you need to click.
If you aren't seeing it then I would recommend canceling your pledge and re-submitting it. This seems to have worked for several of our other patrons.