ThunderBirdVPN 8.0 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. The software belongs to Internet & Network Tools. This free Mac app is a product of tiny studio. We recommend checking the downloaded files with any free antivirus.
From the developer:
VPN: ThunderBird VPN gives you access to all websites and applications using VPN connections. It secures your device’s connection while you’re connected to public WiFi hotspots, cellular data networks, and other public locations. Your password and your personal data are secured and you are protected from hacker attacks.
You may want to check out more software for Mac, such as FileMaker Server, which might be similar to ThunderBirdVPN.