pathauto-8.x-1.x-dev.tar.gz does not contain any .info.yml files.

Experiencing same situation here.

Creating missing file manually did not add any new functionalities to drupal, to latest dev version is not usable.

Agreed, both .zip package and .tgz package return the error: "pathauto-8.x-1.x-dev.tar.gz does not contain any .info.yml files."

This happened on direct download/upload and also install from URL.

Using Drupal 8 RC1

Meanwhile you can use https://github.com/md-systems/pathauto.git

It is not Drupal 8 version of module, there is a mistake.

Yes, still need that module in my d8 project

The version history in Git is somewhat confusing because apparently several fixes for the 7.x branch have been cherry-picked into the 8.x branch (and thus the date for the 8.x-dev package is fairly recent), but essentially the 8.x version here on d.o is still "just" a copy of the 7.x version. Have a look at #2168193: Pathauto for Drupal 8 for info on getting a functional D8 version on drupal.org (and where to find a WIP for it).

A patch that merges the changes from the MD Systems Github fork against the 8.x-1.x-dev release here is available in #2168193.

Closing this as a duplicate, as the patch adds this file and updates the code for Drupal 8.