Steps to set Impersonation Rights for Live Exchange user account for Exchange
2013 and 2016
On the machine where you have installed your Exchange Server, Open the browser (preferably Chrome) and type the URL: https://localhost/ecp & Sign In with Admin Account
Ignore the unsafe error and click the "Proceed to localhost (unsafe)" link as shown below.
Enter the login credentials of your Administrator account with the domain name in the "Exchange Admin Center" login screen.
Click on "Permissions" tab and then double click on the "Discovery Management".
Add "ApplicationImpersonation" Role and then add "Administrator" (the user account for which you want to Impersonate) as Member. Click '+' if you want to add the
members who are having the administrator rights as shown below.
Click the "Save" button to complete the Impersonation Rights setting.