Hi. On Mac (Big Sur) you have to do something like the following:
1. Install OpenJDK via Homebrew. Add necessary folders to your path as instructed.
2. Download JavaFX as instructed above, by Ryan Sturmer
3. Remove the quarantine attribute from the lib folder within the JavaFX download with xattr -r -d com.apple.quarantine ./lib , otherwise you will get security issues while trying to run the app.
4. Run the application with the command as outlined by ryan_sturmer above.