To further explain, the DNA linking in WikiTree is only a reference link. Just like when you link sources to FamilySearch, you provide information that allows others to find your DNA match on the services you've uploaded it too. For public services such as GEDmatch and FTDNA that allow DNA uploading, you link to the kit number of the DNA you uploaded so others who are interested can be linked directly to it. On GEDmatch, it also serves as a two-way link, showing others on GEDmatch that you have a tree on WikiTree.
For private companies such as Ancestry, you can only give your username. This allows others who have also taken Ancestry tests and are a match to find your profile. This only works if you have allowed your matches to see their match to you in your privacy settings.
TLDR; you can't upload your DNA here, but you can link to services that your DNA is already uploaded to.