This document gives you step by step instruction to integrate TFS-2015 with Release Automation and some of the errors I encountered during the integration.
just because you mention VSTS in there as well. everyone who is trying to use that and want to set it up via a service endpoint, you need to make sure, that the required ports are open, that vsts is even able to communicate with your release automation server in your own network, as VSTS is an online system.
Thanks Michael for the comment.
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