Below are the steps to assign app licenses to the users:
- Go to Setup and search for Installed Packages in quick find.
- Locate “Mass File Upload” from the list of installed apps. Click on the Manage Licenses button present on the left of the app name as shown below.
- Now click on Add Users button
- Click on the checkbox next to the user's name to whom you want to assign a license and click Add button.
- Now your users will be able to use the “Mass File Upload” app.