Yes, you can fill app_metadata using your legacy database, but keep in mind this part when writing your script:
If setting
app_metadata, call itmetadatain the script. To support backwards compatibility,app_metadatais calledmetadatain custom DB scripts.
Exactly. The Auth0 datastore isn’t designed to hold that group type data. If you need it in your login ticket, you could use a rule to fetch the data during login. The Auth0 Authorization Extension works the same way.