I have an IPhone that I purchased Norton 360 on I ended the subscription and then bought a multi device license but Apple will not let me load it I must purchase a new licesnse and Norton has been worthless on correcting the problem

I have an IPhone that I purchased Norton 360 on I ended the subscription and then bought a multi device license but Apple will not let me load it I must purchase a new licesnse and Norton has been worthless on correcting the problem What is the fix Note I have not used Itunes much because I can't hear go, now I can hear I want to fix problems and this one is important since I use my phone more than I used to It controls my hear aides