Configure your Jenkins job
1.a. Configure the Bitbucket Repository under the Source Code Management with your credentials. For git:
1.b. In case you are using Mercurial instead of git, configure it as follows:
Please note: the plugin doesn't supports pull requests for Mercurial and the branch, which you want to trigger must be specified in the field Revision.
2. Now activate the plugin in your job selecting the "Build with Bitbucket Push and Pull Request Plugin" option in the Build Triggers pane.