There are several places in the documentation where the version of MonoGame is referenced. In each of these places, the version is hard coded and is sometimes refereed to as 3.8.4 and sometimes as 3.8.4.1. Additionally, the documentation for setting up the preview releases is showing outdated versions as 3.8.4.1-preview.1 while the current preview version at this time is 3.8.5-develop.15.