Just to make sure we are on the same page, you created a template called articles and then you created a page from that template called posts.
if you want to display the content of the posts page, you will need to copy the developer notes for the articles template and add the url parameter posts if you want to display its content.
In the url that you have posted, the url parameter you have set is posts instead of articles.
please post back if you still have any questions.