There is no way to link between FTDNA and Wikitree
Bear in mind also that FTDNA and ancestry.com have a plethora of trees, almost one for each member.
Wikitree only has one tree.
In other words if you go to FTDNA or ancestry.com you will find many trees with the same individual. Not so on wikitree. If there is a duplicate someone will catch it, hopefully, and merge it.
And that brings up a second subject. And that is importing GEDCOM's (family tree files) into Wikitree. I don't know if they still allow it, but I hope not as importing a persons tree creates duplicates which then have to be cleaned up and merged.
I have an extensive data base, over 9,000 persons. However I did not import my data base (GEDCOM, or Family tree). I entered them individually until I ran into a duplicate, profiles created by someone else, then I used that profile.