Getting issue on fqdn confirmation

sprazapati, 

The following document should assist in setting up an MRS Proxy Endpoint. The MRS proxy is commonly the same URL as the Outlook Web Address (example: webmail.contoso.com or mail.contoso.com).

https://docs.microsoft.com/en-us/Exchange/architecture/mailbox-servers/mrs-proxy-endpoint?view=exchserver-2019