You should first ask yourself what you have and what you don´t.
You have the list of items?¿ if not your first problem would be to get all the values. If its a fixed list just copy them to an excel and read it or make it a list in UIPath (Using assign {“Option1”,“Option2”})
Once you have the list next step will be:
2. Upload the files: Use a for each activity defining the item as string and using your list of items. For each of them you can build another workflow where you upload a file alone.
This are just the first steps, next time give us more info about your project and we could give you better help