Problem: If you've uploaded a file directly into a community, there's no way to notify community members by email that the file is available.
Solution: Upload the file to Files first. Then share the file with members of the community, and the community itself. Sharing it with individual members of the community will cause SmartCloud Engage to send email notifying members of the new file. Sharing the file with the community only will cause the file to be placed in the Files location of the Community but will not send an email notification.
Steps
1. Go to Files, and upload and share your file with the community.
For example:

2. In Files, open your file and go to the Sharing tab:

3. Click Add to start adding people who will receive email notification that the file is available.