Before wp installation cmb2-user-select error

[sandrodz]

Fatal error: Uncaught Error: Call to undefined function add_action() in /www/dev.litvurisacxobi.ge/public/mu-plugins/cmb2-user-select/cmb2-user-select.php:106 Stack trace: #0 /www/dev.litvurisacxobi.ge/public/mu-plugins/cmb2-user-select/cmb2-user-select.php(158): WDS_CMB2_User_Select_023->__construct() #1 /www/dev.litvurisacxobi.ge/vendor/composer/autoload_real.php(66): require('/www/dev.litvur...') #2 /www/dev.litvurisacxobi.ge/vendor/composer/autoload_real.php(56): composerRequired8019e99ec0fd9f51454d9a247f6a507('90c7ecedda3d4ff...', '/www/dev.litvur...') #3 /www/dev.litvurisacxobi.ge/vendor/autoload.php(7): ComposerAutoloaderInitd8019e99ec0fd9f51454d9a247f6a507::getLoader() #4 /www/dev.litvurisacxobi.ge/public/wp-config.php(26): require('/www/dev.litvur...') #5 /www/dev.litvurisacxobi.ge/public/wordpress/wp-load.php(42): require_once('/www/dev.litvur...') #6 /www/dev.litvurisacxobi.ge/public/wordpress/wp-blog-header.php(13): require_once('/www/dev.litvur...') #7 /www/dev.litvurisacxobi.ge/public/index.php(37): require( in /www/dev.litvurisacxobi.ge/public/mu-plugins/cmb2-user-select/cmb2-user-select.php on line 106