Use subdirectory (folders) of one domain instead of subdomains?

No, I do not think so. This module is designed to replace multisite installations. Instead, you would have:

en.example.com
fr.example.com
de.example.com

It facilitates multiple shared sites that -- important -- share users and data in common.

See www.skirt.com for the prototype usage of this module.

It is not, however, intended to replace running multiple sites from one code base -- which is the core Drupal multisite behavior.

Take a look at the documentation and test it out a little.

Hi, is this still not possible?

I would like to achieve this heirarchy:

www.first.com
www.first.com/01
www.first.com/02
www.first.com/03
www.second.com
www.third.com
www.fourth.com

All sitest with own design, with one admin place and with some shared content across domains.

Not possible. See https://drupal.org/sandbox/agentrickard/1175752 for the current status and the blockers.

I think this would help some of you.
http://yuriybabenko.com/blog/drupals-domain-access-and-sites-in-subfolders

Is there any progress in this? I checked out the link above and it's more confusing to me