You can install iTunes on a PC with Windows.
Ideally the person should have done all this --> What to do before selling or giving away your iPhone, iPad, or iPod touch [or if you received one that had not been erased] - "Use these steps to remove your personal information from a device, even if you don't have it anymore." --> https://support.apple.com/HT201351
My big concern is it may still be logged into their Apple ID in Find My which means you may quickly finding yourself in a position where you can do nothing with the device.
Turn off Activation Lock. To read more click here --> https://support.apple.com/HT201441 - An activation lock can only be removed using the log-in information for the account that applied the lock.