AEM OOTB Asset Downloaded report can be generated only if following OSGi config is enabled.
- From the web console ([server name]:[port name]/system/console/configMgr), open the Day CQ DAM Event Recorder configuration:
- Select the Asset Downloaded (DOWNLOADED) option in Event Types if not already selected.
- Select “Enables this service”. Save the configuration.
This will make sure when user download the assets it is captured as an activity under that user.
More info :
https://helpx.adobe.com/in/experience-manager/6-5/assets/using/asset-reports.html
https://techrevel.blog/2019/10/13/aem-asset-reports/