From what I can tell, if you're logged into your iCloud account on both your devices you simply do not need it, the devices know it's you. The password is so that someone else can't just log into your HotSpot. If you want to let someone use it then you give them the password to log in with their device. This has been my experience anyway. I've never had to put my password into my iPad to log in, it just connects when I select it.