How do I install the new Office Package purchased from the apple store?

From what sort of medium? If you purchased just a registration code, then you have to download the product from wherever the instructions state. When you first run one of the Office apps you will be asked to provide your registration code.

Please read Writing an effective Apple Support Communities question. We are here to help. We are all users. We are not mind-readers nor clairvoyants. We only know what you write down and tell us. Be specific and thorough. Include your hardware information and installed version of macOS.