How to add botman 2.0 to existing laravel 5.6 project?

I have an existing laravel project. I tried installing botman using "composer require botman/botman" but there are errors preventing me from adding botman:

Problem 1
   - Conclusion: don't install botman/botman 2.3.3
   - Conclusion: don't install botman/botman 2.3.2
   - Conclusion: don't install botman/botman 2.3.1
   - Conclusion: remove symfony/http-foundation v4.1.1

and more lines.

I also tried "composer require botman/studio-addons" but it only use version 1.2 of botman.

via Chebli Mohamed