I can't install it. When i try to open the .msi file windows smart scan prevents it from starting. Is there any way to install it if this happens?
Maybe you can bypass Windows SmartScreen (is that what you meant?). If not, you can try to use the snapshot download instead, which is not an MSI file but a simple .zip file that you can extract somewhere. Being a snapshot, it also includes new features developed for the upcoming Tiled 1.2.