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What needs to be configured to start working with Xray?

1. Issue Mapping - Set which issue types are to be considered requirements & defects
2. Requirement Coverage - Enable requirement coverage at projects that will have requirements that are going to be covered by tests. 
3. Xray Issue Types  - Make Xray issue types available at your projects in order to enable users to create Tests, Test Sets, Test Plans and Test Executions.
4. Setting testable issue (requirement) - set which issue type should be considered a requirement (can be covered by tests)
5. Setting defects - set which issue type should be considered a defect.