Can you try this to see if it works?
To avoid Edge throwing up the user credentials pop up every time, add the URL of your website to the IE intranet zone. Edge shares these settings with IE.
In IE -> Settings -> Internet Options -> Security -> Local intranet -> Sites -> Advanced -> Add
Thanks James for your replay,
but which website shall I add !?
this is happening to all websites
Sorry I have overlooked your initial requirement is to all websites and it's not possible to put *(all) website in the intranet settings. As Microsoft Edge does not support trusted sties. Intranet sites are required for clients using Edge.
What type of frontend authentication are you using? Authentication Server or Explicit Proxy Authentication? Both can use NTLM, AuthServer requires the MWG be added as a trusted site.
The following doc walks you through choosing the right frontend auth method if you are not familiar with them.
In my environment Edge works just fine with NTLM for both Auth Server and Explicit Proxy Auth.
I was using explicit proxy authentication, I changed to authentication server and it worked fine with edge and all other browsers, but I am still confused why!?