best battery low Ringtone mp3

How do I set this as my ringtone for Android:

• Select Download Ringtone button above
• Go to Settings
• Select Sounds & Vibration
• Select Phone ringtone
• Select Ringtone from Internal Storage

How do I set this as my ringtone for iPhone:

• Select Download M4R for iPhone button above and save to your PC or Mac
• Connect your iPhone to your PC or Mac via its charging cable
• Launch iTunes and drag "best battery low Ringtone.m4r" to the Tones folder (Under "On My Device")