EDIT: The instructions assume default Synology install volume of /volume1.  If your location is different use that instead! This is based on the release version of Emby which at the time of writing/video creation was 4.6.3.  The video will become dated so just use the latest DSM 6 Emby version from the website https://emby.media/synology-server.html. If you happen to be running a beta version update to the latest beta version before the DSM 7 update.  The idea is to do any updates on DSM 6