You can download and install Microsoft Office 365 directly from https://outlook.office.com

Once you’re logged into Office in your browser, click on the grid in the upper-left corner of the page:

On the next page, click “Office 365”

Now look to the upper-right and click “Install Office – 365 apps”

The install will download (it’s a big file so may take a while). From there follow the prompts.