To activate the Bitbucket integration click on the Info icon next to the project title either on the dashboard or on your project board and switch to the "Features" tab.
Now click on the green Add button next to the Bitbucket integration to start connecting your project to Bitbucket.
Please click on Authorize your Bitbucket in order to allow modifying tasks right from Bitbucket.
After choosing a repository you can complete tasks and checklist items just by adding the MeisterTask task token (the alphanumeric code in the task URL) to your commit messages in Bitbucket. Checklist items are referenced by number, starting with 1.
You will see different examples on how to add tasks in the integration dialog
Please note: Make sure all people have the same email addresses on MeisterTask and Bitbucket. You need admin rights on the repository to install the integration.