Generating a GitLab access token
- Login into your GitLab account on this website
- Click your profile icon at the top-right corner and choose Preferences:
- Click Access Tokens at the left menu You'll be greeted with this page:
Here you have to click on the cross at "Expiration date" box first, then name your token something with the name you like the most ("cool gitlab token for my home PC" perhaps):
Check all the scope checkboxes and then click "Create personal access token"
Your personal token will appear now at the top of the page:
Click on copy button (the most right button as shown on screenshot) and put it somewhere temporary (don't try to remember it please)
Pulling the full repository
You can clone a repo with a Github Desktop (yes.) or another preferenced application.
Remember: about 962MB will be downloaded from the repo.
Pulling with Github Desktop
Download and install Github Desktop. The URL for the full repo: https://gitlab.com/leaknet/leaknet-full.git
Your GD's clone window should look like about that: 
Authentication window:
Use your GitLab username as the username, and your previously created access token as your password
Add submodules to Github Desktop
Your Github Desktop window should look like this at this point: 
Now you have to manually add each submodule folders from the pulled repo. For it, you should click on Add button at the top of the window, and then choose "Add existing repository...":
Then you have to add following folders from pulled repo:
- cstrike
- hl1
- hl2
- hl3
- tf2
After doing that, your GD window should look like this:
Switching to the latest branch revisions
Due to Git, manually added repositories from the list above will be "detached" from their HEADs. That's really funny thing (honestly). For you to be able to use the latest revisions of the code or other submodules, you need to manually go through each repo from the list at the left side of your GD window, and choose the branch accordingly:
cstrike - master
hl1 - master
hl2 - master
hl3 - master
src_main - rewrite
tf2 - master
Now your pulled repo should be up and running.