Create mu-plugins folder
mkdir wp-content/mu-plugins
Download the plugin into mu-plugin
wget https://raw.githubusercontent.com/weDevsOfficial/plugin-demo/master/demo.php -O wp-content/mu-plugins/demo.php
define( 'WP_DEBUG', false );
define( 'WP_DEBUG_LOG', false );
define( 'WP_DEBUG_DISPLAY', false );
define( 'WP_SITEURL', 'https://site.com' );
define( 'WP_HOME', 'https://site.com' );
define( 'WP_AUTO_UPDATE_CORE', true );
define( 'DISALLOW_FILE_EDIT', true );
// disable the menu and capability
define( 'DISABLE_THEME', true );
define( 'DISABLE_USERS', true );
define( 'DISABLE_SETTINGS', true );
define( 'DISABLE_TOOLS', true );
define( 'DISABLE_PLUGINS', true );