tl;dr: Write a new blog on CF (you don't have to post it), add a line
[tutorial: <problem id>] (e.g.
[tutorial: 1336A]), and preview it.
This tag fetches the tutorial from Polygon. After the problem is added to the problemset, anyone can get it. However, you can't get it if the authors haven't written the tutorial, or they didn't write it on Polygon.
But, why don't authors publish the tutorial even if they've finished writing the tutorials?
There can be many reasons:
The tutorials of one or two problems are still under construction, while the tutorials of other problems are finished.
The tutorial is written, but not completely finished yet. For example, there may be some grammar mistakes, maybe it's not very easy to understand. The authors may want to make the tutorial better before publishing it.
However, if you don't mind reading a non-finished tutorial which may be hard to understand with some mistakes, this method may be helpful for you.