Install Commit Hub for JIRA Connector plugin
In order integrate Bitbucket repositories with Commit Hub plugin for JIRA You must download and install free Commit Hub for JIRA Connector plugin: https://marketplace.atlassian.com/apps/1221883/commit-hub-for-jira-connector
After successful installation of plugin You have to enable Hook in repository. If You are not familiar with hook setup please check Atlassian guide: https://confluence.atlassian.com/bitbucketserver/using-repository-hooks-776639836.html
When you enter Hook setup for Your repository You shuld notice Commit Hub hook:
When You enable Commit Hub Hook configuration popup will be down to enter JIRA address, Ruleset ID and Authorization Token which can be obtained from Commit Hub ruleset configuration screen in jira.
After clicking enable you are done.