Windows is caching previous installer when updating from previous versions, the result is a botched install.
The issue is solved now and you can download it from main web page as usual; also try not to install on protected folders that requires admin privileges.
About Win 10 smart screen filter, it seems that Microsoft has a database from applications downloaded from Internet and it will take some time until it is 'trusted'.
This is how the installer should look, (notice 'v3.0' text, if it doesn't look like this please contact us)
Linux and Windows versions are available (64 bits), please download at http://worldcoin.global/worldcoin-quick-start/
Don't forget to open README file! http://worldcoin.global/wallets/README_PLEASE.pdf
[Fixed] -- Windows 10 compatibility issues with Windows 10 (incorrect rendering)
[Fixed] -- Fixed bug in 'Address Detail' component that didn't display all addresses in some circumstances
[Component] -- Added 'Transaction List' component that displays last N transactions (parameter N can be changed and saved)
[Component] -- Added functionality in 'Encrypt Wallet' component that allows to change the encryption password