How to connect to TFS 2015, I am using 12.9.0.71 TOAD 64 Bit.
A good place to start would be the Getting Started With Team Coding guide, which can be located here:
http://www.toadworld.com/members/john-pocknell/blogs#post-15929
There’s also a link on that page that can help you set up a connection to Team Foundation Server, but the related link is based on Toad 12.8 (which is before the rewrite of Team Coding). As a result, the screenshots may be different. If you follow the “Getting Started Guide” and simply make sure you select “Microsoft Team Foundation Server” as your VCS, you should be good. You’ll need to click the ellipsis button ("…") next to the VCS drop-down to enter the name of your TFS server and its default collection. I’d recommend talking to your TFS administrator to see if any of the default TFS server settings in Toad need to be changed. Plus, if all you need is Source Control and Work Item tracking functionality, the internal client will most likely be the most efficient.
Let us know if you have any further questions on it!
-John