In order to shadow in as another employee within your organization, you must first add the Login as Employee button to the Employee Information screen.
Navigate to Team > My Team > Employee Information
Once you are on the Employee Information Screen, click on the actions ellipsis on the right hand side of the screen and select Add/Remove Columns.
Inside of the Add/Remove Columns screen, use the search bar to find Button: Login as Employee from the list of Available Columns and Add to the list of Current Columns.
Use the Up Arrow to move the Button to the top of the list so that it appears alongside the other employee actions buttons and then Apply.
On the Employee Information screen, you'll now have a new Login As Employee button. Click on that button and the applicable employee's profile will open up in a new tab.

There is a very clear message at the top of the new screen that displays You are Logged in as Employee's Name.
In order to navigate out of the employee's view, close the Browser Tab.