From EW faqs:
Will I be able to upgrade to the Opus engine without buying Hollywood Orchestra Opus Edition?
Currently you must purchase Hollywood Orchestra Opus Edition to get the OPUS software. People who purchase any other EastWest product post-release will also get OPUS. All ComposerCloud members will automatically get OPUS. But we are going to wait a while before allowing previous PLAY product purchasers to upgrade in order to assist our support team during this major upgrade period. When we do provide that option, it will be a paid upgrade.