I have tried to install this version and earlier versions and get the same error. The details are:
An error occurred trying to download 'https://www.methodintegration.com/MethodOutlookAddIn/Web/OutlookMethodSync.vsto'.
See the setup log file located at 'C:\Users\Mike\AppData\Local\Temp\VSDAD64.tmp\install.log' for more information.
I have set it as a trusted site on IE and run it as an administrator. Win 7-64bit machine.