Laravel - Artisan not working

You need to run composer install, so the composer refresh all dependencies, artisan's begin on the middle. That should do the job!

Generally speaking, the vendor directory is not committed to VCS, as such, doing a clone on a standard Laravel app won't include all its dependencies.

Once you have cloned, doing composer install (or composer update if you want the latest packages as a developer) will fetch the dependencies and allow your app to work.