Allow installing via UI (experimental) on Linux fails

Problem/Motivation

After installing Project browser, there are several steps to follow in order to be able to install modules from the UI.

Steps to reproduce

Install Project Browser via composer: composer require 'drupal/project_browser:^2.1@beta'

Proposed resolution

After installing the option to install via UI is not enabled.
1. First you need to install and enable automatic_updates →
2. Go to: /admin/config/development/project_browser and enable: Allow installing via UI (experimental)
3. Make sure folders and files are writable by drupal (chmod 2775 . && find . -type d -exec chmod 2775 {} \; and find . -type f -exec chmod 0664 {} \; and also set ownership on folders)
4. In settings.php add: set $config['package_manager.settings']['include_unknown_files_in_project_root'] = TRUE;

Without the last setting you will get a 504 timeout. This should probably be fixed in the module.