Integration with professional code review tools automatically links commits to review results, and links enhancements and Tasks to current or completed reviews, so you can jump to the code review system, for example Gitlab. The review status of a Requirement or Task can be used in lifecycle settings as a control that review is completed before the Requirement or Task status changes.
Inside the project, open Settings — Integrations and add the Gitlab integration:
You can review how the integration is working on the Additional tab.
A working integration starts filling the "Review" module with items that correspond to merge requests created in Gitlab.
For more on using review tools in development, see: Code Review