This is one of the simple things that I find myself Googling every time I need it. For some reason I never seem to remember the location of the FederationMetadata.xml in ADFS. So here goes, this is the location you’re looking for.
https://server.domain.com/FederationMetadata/2007-06/FederationMetadata.xml
The location will be the same regardless of the ADFS version. The metadata should be accessible from the internet it the ADFS is setup with internet facing WAPs.