Authenticate/log in to the NAS as necessary. Here's how I solved the issue and successfully restored: The issue that I and others have encountered is that when you get to the point in the Migration Assistant when you choose a backup to migrate from, you're able to see the NAS on the network as an option, but upon choosing it and the backup directory, the result is the message 'no volumes found in backup' resulting in a dead end. In my case, I bought a new Mac and wanted to migrate from my old Mac (which had died).

The issue is migrating from a Synology NAS Time Machine backup on a Mac. I was unable to find a clear answer anywhere as to how to do this so I though I'd post this solution.