We’ll guide you on how to configure Xray in your Data Center (DC) instance.
Xray Addon must have been previously installed by your Jira Admin through the Atlassian Marketplace. More info here.
Add Xray to an existent project
Configure Requirements & Defects
Access "Jira Administration" 
, and Navigate into Xray settings under Manage Apps.
Select the option "Issue Type Mapping"
Enable Xray Requirement Coverage
Go to your Project Settings → Summary
From the top right corner select the button "Actions" → "Set Enable Xray Requirement Coverage"
(Video Description: Set Enable Xray Requirement Coverage)
Add Xray Issue Types
Go to your Project Settings → Summary
From the top right corner select the button "Actions" → "Add Xray Issue Types"
(Video Description: Set Enable Xray Requirement Coverage)
Use Xray Test Project template
From the top menu, select "Projects" → "Create a Project"
(Video Description: Create an Xray Test Project)