Version 16.8 refers to a release from August 2016. At the time, this was a major update. According to historical Ross-Tech release notes, VCDS 16.8 introduced:
Ross-Tech maintains an archive of older versions on their website. Navigate to the "Downloads" section on Ross-Tech dot com. Look for "Old Versions" or "Legacy Downloads." vcds 16.8 download
Official downloads come with MD5 or SHA256 checksums. Compare the hash of the downloaded file to ensure it hasn't been tampered with. Version 16