Approved for what? You don't need anything from Microsoft. RwDrv.sys is not signed by Microsoft. Whoever made you believe this was 100% wrong.
Did you read the article?
Did you google what I said?
Digicert is the approval agency for the cert (they issue it after you pass ID validation), you know the one you linked. You need to pass their validation. Looks like rwdrv is cross-signed by globalsign, and also subject to the older sha1 algorithm that is no longer allowed for new signatures.
Of course it is not signed by microsoft, it's signed by the applicant. It must be cross-signed by microsofts root cert agencies to be used in modern Windows though. The agencies that review these are supposedly monitored and subject to review from microsoft, but that's really kinda where things break down.
This used to be more lax but Microsoft tightened it a lot recently. And you can no longer apply under the old system. Or renew. The issue is the old drivers running around are exploitable in many ways... and signing review itself still is a joke after ID validation.