1.8.0b1 is a pre-release (beta) version, the actual finished version of 1.8.0 is not available yet.
Pre-release versions must be downloaded manually instead of from within the editor because they may have unfinished features or additional bugs.
The download link can be found on the news post for the update. Some new features also require the beta version of one of the voices that are being updated (link also included below).
Not all voices have a pre-release version, and AHS pre-releases are being distributed through the AHS “My Page” instead of by Dreamtonics.