PrerequisiteComposer need to be available in your windows machine
Update composer with below packagecomposer require symfony/var-dumper:v2.7
composer remove phpdocumentor/reflection-docblock:3.1.1
composer remove drush/drush:8.x-dev
Note: If you still face an issue, read composer error message, it provides details about what is missing in your installation.
- Installation request for drush/drush 8.x-dev -> satisfiable by drush/drush[8.x-dev].
- drush/drush 8.x-dev requires phpdocumentor/reflection-docblock ^2.0 -> satisfiable by phpdocumentor/reflection-docblock[2.0.0, 2.0.0a1, 2.0.0a2, 2.0.0a3, 2.0.1, 2.0.2, 2.0.3, 2.0.4, 2.0.5] but these conflict with your requirements or minimum-stability.