Do I have to download on the phone I need to spy on or can I download it on my phone and spy from phone I want to spy on?

Do I have to download on the phone I need to spy on or can I download it on my phone and spy from phone I want to spy on?

Yes, you need to install the TiSPY application on the phone which you want to monitor.
After successfully install and register application on the device you can monitor your device at https://tispy.net/