Computer Configuration > Administrative Templates > Google Chrome - Default Settings (users can override)
Both
HKLM\Software\Policies\Google\Chrome\Recommended
Setting the policy sets up the directory Chrome uses for downloading files. It uses the provided directory, whether or not users specify one or turned on the flag to be prompted for download location every time. This policy overrides the DefaultDownloadDirectory policy. Leaving the policy unset means Chrome uses the default download directory, and users can change it. On Google ChromeOS it's possible to set it only to Google Drive directories. Note: See a list of variables you can use ( https://www.chromium.org/administrators/policy-list-3/user-data-directory-variables ). Example value: /home/${user_name}/Downloads