I understand that the problem has been solved in the meantime.
For future reference:
- Open the link from your license e-mail in your web browser, the download should start immediately into your Downloads folder. I tested the latest versions of Safari, Chrome, and Firefox, and the downloads worked fine in those browsers.
- Avoid third-party download managers.
- Simply double-click the file, Glyphs should respond with a Thank You dialog.
- You may have to restart the app once afterwards.