You downloaded the version because you need mods. Modern mods (v1.50+) will crash v1.4.5. You need "legacy mods."
If playing via Steam, keep an eye on your update settings so Steam doesn't automatically bump you back to the latest live version overnight. i euro truck simulator 2 version 145 download new
If you own ETS2 on Steam, you can technically revert to 1.4.5, but it is hidden. You downloaded the version because you need mods