Maatwebsite laravel-excel installation

I'm having problem when installing laravel-excel maatwebsite. In the installation instruction it says I should require "maatwebsite/excel": "~2.0" in composer.json and update my composer. But when I'm updating my composer it says

[UnexpectedValueException] Could not parse version constraint 4.x.x: Invalid version string "4.x.x"

and when I run php artisan vendor:publish it says [Symfony\Component\Debug\Exception\FatalErrorException] Class 'Maatwebsite\Excel\ExcelServiceProvider' not found

I don't know why

via Chebli Mohamed