It sounds like you’re trying to download the Twinmotion 2018 macOS installer, but the download isn’t starting — no prompt, no progress, just “Aucun téléchargement” (No download).
Would you like help finding the correct official download for your Mac’s OS version?
Here’s a helpful response you could send to someone reporting this issue (or to use as a support feature explanation): Troubleshooting "Aucun téléchargement" for Twinmotion-2018.0.7502-macOS.zip