How can I download Microsoft Office Mac on MacBook Air early 2014?

You can go to the AppStore

or

You can go to Microsoft’s website, log in with your Microsoft Account (if you don’t have one, you can create an account) and subscribe to Office 365

or

you can give the free LibreOffice for Mac a try https://www.libreoffice.org/discover/libreoffice/ ( it works fine together with Office files)

or

you can give the apps Pages, Numbers and Keynote a try ( these apps are already on your Mac)

Go online and you can download Office 2019 for Mac. Here is one link:

https://www.amazon.com/Microsoft-Office-Student-Windows-Download/dp/B07H4XBM1R/ref=sr_1_3?dchild=1&keywords=office+2019+for+mac&qid=1624280688&sr=8-3