updating microsoft word on mac after catalina update

Microsoft Office 2019 and Microsoft Office 365 work with Catalina. Neither are free. Office 2019 is a one time payment and Office 365 is a subscription. Microsoft Office Purchase Site

Free options, although not 100% compatible with Microsoft Office include:

LibreOffice

GoogleDocs

Office Online

.

.

.

.

office 365 id rent so it's an ongoing expense

office 2019 is one time fee

libreoffice is free and support ms office files

Microsoft 365 is a subscription app, Office 2019 is a one off payment.

Libre Office is free, https://www.libreoffice.org

Install it and find out.

If you are asking about LibreOffice, it is not 100% compatible. Not all formatting may work.