To download a database file from the FileMaker Server Admin Console:

• open the admin console at https://<votre-sous-domaine>.fmcloud.fm/admin-console
• authenticate using your FileMaker Server login/password
• go to Databases
• close the file using the contextual menu
  
  
• once the file is closed, select Download from the same menu
• since FileMaker Server 19, the download does not start immediately, you need to go to the notification menu on the upper right corner.