As people have explained in the comments, that tag might not be appropriate for Super User. If you were going to create it (and I would suggest based on those comments that you don't), you could deal with the length limit by partially abbreviating it, e.g. [tag:vs-team-services]. The tag wiki excerpt would then clarify what exactly the tag is about, and people would likely associate Visual Studio with the phrase "team services", whereas I wouldn't immediately have a guess about [tag:vsts].

Also, the reason you're receiving that error message is that [tags differing only in hyphenation or capitalization are no longer allowed](http://meta.stackoverflow.com/q/251478/2825369). If I understand correctly, only moderators can create tags that would be blocked by that check (there are legitimate exceptions to the rule, like [tag:windows] and [tag:window]).