Install Error on bakery - PHP Fatal error: Uncaught Error: Class ‘Slim\Container’

I am using Amazon Linux with Apaches 2.4 and PHP 7.0.29. Getting Class not found error on install.

php bakery bake
PHP Fatal error: Uncaught Error: Class ‘Slim\Container’ not found in /var/www/html/userfrosting/app/system/UserFrosting.php:35
Stack trace:
#0 /var/www/html/userfrosting/app/system/Bakery/Bakery.php(46): UserFrosting\System\UserFrosting->__construct()
#1 /var/www/html/userfrosting/bakery(33): UserFrosting\System\Bakery\Bakery->__construct()
#2 {main}
thrown in /var/www/html/userfrosting/app/system/UserFrosting.php on line 35

It sounds like maybe you forgot to run composer install first?