Want something you can use in a web browser without downloading anything? Google Workspace (formerly G Suite) apps are also free, with Docs, Sheets and Slides all capable alternatives to Office apps.
There’s no catch – it’s open source, free software. One example is LibreOffice, which is a fully-fledged, suite, complete with alternatives to Word, Excel, PowerPoint and more. The good news is that you can get a perfectly good free alternative which is still compatible with Microsoft Office document formats. Each license only usually covers one machine. Old physical copies are likely to be available on eBay and similar sites, but make sure it’s not already been activated. Microsoft has never made Office available as a completely free product, so expect to pay if you want access to its capabilities.