• From Setup, enter Installed Packages in the Quick Find box, then select Installed Packages to find the installed package that has available licenses.
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• Click the Manage Licenses link next to the Mass File Download name.
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• Click "Add Users."
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• Choose a view from the drop-down list, or click "Create New View" to build a new custom view.
• Click a letter to filter the users with the last name that corresponds with that letter, or click All to display all users who match the criteria of the current view.
• Select users.
• To select individual users, use the checkboxes. Selected users are listed in the Selected list. When the list includes all the users to whom you want to assign licenses, click Add. 
• To select all users for the current view, click Add All Users, then click OK.
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