How can I access old Office for Mac windows files? They are 32 bit.

You can access previous versions of Office files in a variety of ways.

If you have an early version of Office for Mac 2016, you can update it at no charge. See: https://docs.microsoft.com/en-us/office365/troubleshoot/administration/office-2016-for-mac-64-bit-upgrade

If you have Office for Mac 2011 or earlier, you can either subscribe to Microsoft 365 or you can make a one-time purchase. See: https://products.office.com/en-us/buy/compare-microsoft-office-products-for-mac?ms.officeurl=mac-compare-redir

Or use the free Microsoft Office on the web: https://products.office.com/en-us/free-office-online-for-the-web

Or Google Docs: https://www.google.com/docs/about/

Other options include using the free and very good Libre Office https://www.libreoffice.org/

or Apple's Pages and Numbers

Files are not 32 or 64 bits, programs are.

You can open most Office documents either with Office itself, or iWork (Pages, Keynote and Numbers can open Word, Powerpoint or Excel documents, respectively) or LibreOffice, OpenOffice or variants thereof.

All but the actual Microsoft Office are free, too.