Can't Install Ui Package

I've just downloaded the laravel 6 and I'm trying to install composer require laravel/ui package, but I'm getting the following composer error:

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Conclusion: remove laravel/framework v6.18.3
    - Conclusion: don't install laravel/framework v6.18.3

That's because you're using Laravel 6 and the package you're trying to require wants Laravel 7.

If you change the composer require line to this:

composer require laravel/ui:^1.0 --dev

It should download the correct package you need.

Edit: If you see this error in the future, the best thing you can do is go to the repository of said package (in this case this repo) and open the composer.json of said repo and see what the requirements for the package are. In this case I linked the composer.json of the most recent release, which states it needs Laravel 7.