To configure the MetaDataEndpoing URL you must navigate to Setup and type Remote Site Settings in the quick find box.
Here you will see the MetaDataEndPoint field and you will click on Edit. This will pop up three editable fields where you will enter your Domain URL into Remote Site URL field and click Save.
Your domain URL can be found on the Home tab of ExAM when in Salesforce Classic. It will be displayed in your URL, but it is only the section from https through .com. For example, the URL that you see displayed might look like this “https://examdemo.my.salesforce.com/home/home.jsp” but the portion that you are copying and entering is only “https://examdemo.my.salesforce.com”.