Once the User is created, go to HR > Main > Employees.
Select the Employee, and click on Link User to Employee.
You will then be prompted with the following screen:
It is important to remove the automatically suggested username, in the 'User name' field. This will enable the search bar at the bottom of the window.
Use the search bar to search for the newly created user. You can click on the magnifying glass icon to display a list of created users. In the latter case, select the User and click OK.
You may now notice that you cannot amend the Username, Password and Email fields, as these are now populated by the information you have inputted in the User you are about to link. Click on Link to finish this process.