Most accounts from public databases will fail verification immediately. You’re wasting time.
Once installed, you can add your account details (for services like Real-Debrid, Premiumize, or specific hosters) to unlock full speeds and parallel downloads. JDownloader Where should I buy and enter my (Premium) Accounts jdownloader 2 premium database premium account install
Before diving into the "premium database" aspect, you must understand the software itself. Most accounts from public databases will fail verification