How can I create Test case from Requirement?

There are two ways to do it.

Option 1:

• Open Requirement
• Click on gear option
• Click on 'Create Test Case from Requirement'
• This will create a Test Case and auto link to the requirement. 

Option 2:

• Open Requirement
• Open linked Test Cases section

• Click on Link
• Click on Create Test Case

• This will open up the new tab in your browser to create Test Case.
• Once Test Case is created, you can go to the previous tab of your requirement.
• Click on the refresh button to reflect the Test case in Link Test Cases window.
• Select the Test Case to link.
• Click on Link/Link & Close.

• This will create a Test Case and auto link to the requirement.