Offline installer is up, and as expected is a complete reinstall.
You can Overwrite the Alpha, but not update it.
I recommend leaving the alpha folder but deleting all the contents.

Installer will then use your Current Divinity Original Sin II location by default, but still be a fully new installation.
I'd also recommend deleting all the Alpha saves, and settings, to start from scratch.

Alpha Saves can't be used anyway.

Larian's also just announced only english version released today.
Last minute issues with other Languages, mean they are delayed by one week.

My installer just finished, time to play.