To develop in the admin interface read the related README.
To develop in the geoportal part you should create a new application, Then have a look on the application debugging to be able to have your checkouted code running in the application.
Install the pre-commit hooks with::
pip install pre-commit
pre-commit install --allow-missing-config
Don't worry about the time take on the first run
Careful: If the pre-commit fail the commit will be aborted.
Commit without pre-commit
git commit (-n|--no-verify)
More information on pre-commit.