When talking about technology such as computers, mobile phones, and tablets, the normal conventions when using on and in do not strictly apply.
When talking about hardware, you would install it into the device. However, when talking about software, would install it onto the device.
If you think of software such as word processing software, you are installing it onto the device because, the software is a bolt-on to the operating system software (Windows, Linux, iOS...) as opposed to being incorporated with the operating system software, to enable the computer to do what you want it to do.
Hardware is something which is added to the system inside the device and being incorporated with the system. This is why hardware is installed into the device.