Anycount 4D and 2021 are fully compatible.

Versions 3D, 8 and 7 are compatiblewith windows 10 itself, but may experience compatibility issues with the latests builds of Microsoft Office.

Version 6 and earlier are incompatible. 

You can download a free 30-day trial of Anycount 4D here: https://www.anycount.com/try-free/ 

You can purchase a new license or an upgrade from an old license here: https://www.translation3000.com/product-category/word-count/