How to create something similar to GDB in QGIS?

You can achieve this by preparing all those layers in one (or more) project files. Share these projects on the network and you can load them using Layer - Embed Layers and Groups.

If you want to change anything in these layers, open the original project file and changes will appear in all projects that contain embedded layers.

In Addtion to saving defined layer styles within project files on the network, you can create a single Spatialite enabled database.sqlite, if your workflow isn't too busy.

For myself, I've replicated a fgdb by importing a hundred shapefiles and a couple hundred datatables, with great performance. Spatialite won't allow for PostGIS or FileGDB style mutli-user editing across the network, but you can easily export layers from it, then when finished import it back. Create a shared spreadsheet that tracks who's working on which layer. The advantage is that project can have a single file (not a whole directory) that's easily emailed, backed up, etc. Read the quote below from SQLite FAQ before proceeding..

" Multiple processes can have the same database open at the same time. Multiple processes can be doing a SELECT at the same time. But only one process can be making changes to the database at any moment in time, however.

SQLite uses reader/writer locks to control access to the database. (Under Win95/98/ME which lacks support for reader/writer locks, a probabilistic simulation is used instead.) But use caution: this locking mechanism might not work correctly if the database file is kept on an NFS filesystem. This is because fcntl() file locking is broken on many NFS implementations. You should avoid putting SQLite database files on NFS if multiple processes might try to access the file at the same time. On Windows, Microsoft's documentation says that locking may not work under FAT filesystems if you are not running the Share.exe daemon. People who have a lot of experience with Windows tell me that file locking of network files is very buggy and is not dependable. If what they say is true, sharing an SQLite database between two or more Windows machines might cause unexpected problems. " -- http://www.sqlite.org/faq.html#q5