That’s not what the release notes say:
(The 32-bit version installs by default to C:\Program Files (x86)\Scrivener on administrator accounts; the 64-bit version installs to C:\Program Files\Scrivener. Please be sure to uninstall previous betas before installing Beta 3.)
From Scrivener 3.0 Beta - Release Candidate 10 (Download Links & Change List)