I can't use my Apple iPhone Xs Max iOS 12.0 as a personal hotspot
Cause 2 of 2: The password used on the other device is incorrect
To use your phone as a personal hotspot, you need to key in the password you selected when you set up your phone as a personal hotspot on the other device.
Solution: Check the password for the hotspot on your phone and key in the correct password on the other device.