Content (books, songs, movies) you have purchased or installed from iTunes on your Mac computer might not be transferred automatically to iPhone. Make sure all of your data and apps are properly backed up. You can transfer purchases manually before syncing your device. In order to Transfer Purchases from iTunes to iPhone follow these steps:
Step 1: Navigate to account option on top right panel of Mac computer. (Sign in with your apple id and password if required). Select the purchases option. All purchases include books, songs and movies. Hit the download symbol.
Step 2: If you need to transfer all items then hit download located at right bottom corner. It will download all the purchases to iTunes library. Now connect your iPhone to iTunes.
Step 3: Go to iPhone symbol. Hit sync (It might ask you to authorize the computer, you have to simply go to menu bar and enter apple id & password for authentication). Your purchases will be transferred to iPhone after sync process.
Hopefully, these steps are useful for you. If not or you need further assistance then get in touch with tech team for more support through our toll free number 1-855-602-7997.