You can use Home Sharing to import items from up to five iTunes libraries on other computers. To use Home Sharing, you must have an Apple ID.
Any time you download an item from Apple Music or the iTunes Store to a computer in your Home Sharing network, you can have the item automatically downloaded to the other computers in the network as well.
Follow these steps on each computer you want to include in your Home Sharing network.
Choose File > Home Sharing > Turn On Home Sharing.
Type your Apple ID and password, and click Turn On Home Sharing.
If you don’t have an Apple ID, click “Don’t have an Apple ID?” and follow the onscreen instructions.
Important: Computers you import from must be on, with iTunes open.
Click 
near the top left of the iTunes window, then choose a shared library.
If you don’t see any shared libraries, choose Edit Menu, select Shared Libraries, then click Done.
Click the Show pop-up menu at the bottom of the iTunes window and choose “Items not in my library.”
Select the items you want to import, and click Import.
Click near the top left of the iTunes window, then choose a shared library.
If you don’t see any shared libraries, choose Edit Menu, select Shared Libraries, then click Done.
Click Settings at the bottom of the window.
Select the types of content you want to automatically import.
Click OK.
On each computer, choose File > Home Sharing > Turn Off Home Sharing.
If a shared computer doesn’t appear when Home Sharing is on, turn Home Sharing off, and then turn it on again.