You are just seeing a factual statement the VRDB hasn't been generated yet, so I suggest you run a manual Generate VRDB Now! then the splash screen will report the date that it was last generated.
This is likely to take a little time for the first time you run it, so I suggest you start it at a time when you can leave it for 15 minutes or so, go and have your evening meal or something.
I suggest a little time browsing the avast help file to get the best from avast!