Watch old software versions which install "not signed" drivers.
You must use a recent software version, which install signed drivers.
The usual problem is: if you have already installed an old software version, then this is very difficult to force the operating system to use the new driver.
In the property window of the Cable SYS file ("ftdibus.sys"), you must see this:
If you do not see this, this means, you still have an old driver installed.