This release of BI Developer Extensions for Visual Studio 2017 is not the latest. It is compatible with an older version of SSDT (15.8.2) or earlier.
The "BI.Developer.Extensions.2.2.1.for.VS2017.vsix" download is not recommended since it is not the latest. It is made available in case you need to install a historical version of BI Developer Extensions with an older SSDT. To prevent auto upgrade to the latest version, disable "automatically upgrade this extension" in Tools... Extensions and Updates.