Access the following link

https://setup.office.com/

Log in with your Microsoft account

• For certain versions of Home & Business, especially for MacOS, a Microsoft account is required

Then enter the activation key

• After entering the key, a download may start automatically
• If a download did not start automatically, continue with the following steps.

Download and install Office Home & Business

• After activating the product, look for the 'Install apps' button in the top right corner.
• Select Office Home & Business (or individual apps) and download the file.
• Run the downloaded file and follow the installation steps.

After installation, you need to activate Office

• Open Word or Excel.
• If prompted for authentication, log in with the same account you used to activate the key.

Office is activated

• The product can be used.