You may link a bug to a requirement version. Click on the bugs icon on the right vertical menu. Click on the New/Link button to expand a dropdown with options to link an already existing bug or create a new bug.
To link an existing bug, click Link Bugs in the dropdown, then click on the desired bugs to link. The bugs that will be linked will appear on the right side of the pop-up. Click on Add to link them to the requirement version.
You can also create a new bug and have it automatically linked to the version by clicking + New Bug in the dropdown instead. Add a title and click Save. To edit the details of the bug, click on the bug ID to open the bug details.
To unlink a bug from the requirement version's bug tab , click on the vertical menu for the desired bug and choose Remove.
Alternately, you may remove a bug from the bug's details window by clicking the when you hover your mouse over the requirement, which is listed in the Requirements section.
Users will need to have project permissions to view and edit in both Requirements and Bugs to perform this action. Depending on the settings of the user's project permissions, they may be able to view all the project requirements and project bugs, or just a subset of each. Users added to a specific requirement as a contributor or reviewer, and users added to a specific bug as a watcher will be able to view them.