...
Pressing Upload will upload the selected files and create the rule. The hash fingerprint of the file is shown alongside a preview of the file (if it is an image). The Last Seen and Times columns will show you how many times the excluded file has been seen in your instance and when it was last seen.
...
Create field options
Project
This defines the projects that this exclusion should be applied to. Global means that it will be applied to all Projects.
Files
This is where you select individual files that you would like to exclude. You can select up to 20 files at once.
Zip Files
This allows you to upload a Zip file that contains all of the attachments that you would like to exclude. This Zip file must be less than 10MB