easyBTX is an indie app and currently unsigned (no paid signing certificate), so your computer warns you the first time. That's expected for small indie apps, and you only clear it once.

On Mac you get one of two messages, depending on your macOS version. Both are the same underlying thing, an unsigned app carrying the "downloaded from the internet" tag, and both clear once.

Most often, macOS says easyBTX is "damaged and can't be opened." It is not damaged. Drag easyBTX into your Applications folder, then run this once in Terminal (Applications → Utilities → Terminal):

xattr -dr com.apple.quarantine /Applications/easyBTX.app

Then open easyBTX normally. That command only clears the download tag macOS adds to unsigned apps. It does not change the app.

If instead macOS says it "can't verify the developer":

1. Double-click easyBTX. When macOS blocks it, click Done.
2. Open System Settings → Privacy & Security.
3. Scroll down to the easyBTX notice and click Open Anyway.
4. Confirm with Touch ID or your password. You only do this once.

On Windows, easyBTX runs through WSL2, the faster Linux engine, so there's no separate Windows installer and no SmartScreen prompt. The download is the Linux build; follow the Windows / WSL2 steps on the install page to set it up. Every command is copy-paste, and from then on it updates itself.