If you want someone to view a file but not be able to download it, you must adjust the link settings manually.
Sharing a link for viewing usually allows the recipient to both see the content and download a local copy . While "view-only" implies that the original file cannot be edited or deleted by the recipient, downloading is a standard feature of these links unless the owner explicitly disables it. How Dropbox Shared Links Work dropbox link for viewing can download
By default, anyone with a view-only link can click the Download button in the top-right corner to save the file or folder to their own device. If you want someone to view a file
Recipients can preview the file in their web browser without needing a Dropbox account. How Dropbox Shared Links Work By default, anyone
When you generate a shared link in Dropbox, you are essentially creating a public or semi-private doorway to your data.
In a shared folder, "Can view" (read-only) members can still download and share files, but they cannot modify the version stored in your cloud. How to Allow or Disable Downloads