EA has abandoned this demo. Downloading it exists in a legal gray area (abandonware). However, always scan your downloaded .exe with Malwarebytes for Windows 7. Avoid any website asking for a "password" or offering a "crack" for a demo—the demo was always free; if a site asks for payment, close the tab.
The best and safest way to download the FIFA 15 demo is from the official EA Sports website or the game's page on Origin (EA's digital distribution platform). fifa 15 demo download windows 7
Sites like Softonic or Evo-Web often host historical game files and installers . EA has abandoned this demo