It does skip the installation procedure, but it gives another error.
When I try to "Load Octane":

EntryPointNotFoundException: LoadLibrary
Octane.DynamicLibrary.Load ()
Octane.PluginDllLoader.LoadLibraries ()
OctaneUnity.PluginController.Init ()
OctaneUnity.LicenseManager+<>c ...

I skipped (twice). No errors.
The Octane menu only shows "Settings".
Then I try to "Load Octane", and...

EntryPointNotFoundException: LoadLibrary
Octane.DynamicLibrary.Load ()
Octane.PluginDllLoader.LoadLibraries ()
OctaneUnity.PluginController.Init ()
OctaneUnity.PreferenceWindow.OnGUI ()
System ...

When I try to install Octane in the latest Unity (on a new project) this error happens:

Failed add install extension to unity: 1
UnityEngine.Debug:LogErrorFormat(String, Object[])
OctaneUnity.ExtensionInstaller:InstallExtension()
OctaneUnity.InstallChecker:UpdateOnce()
UnityEditor.EditorApplication ...