Issue with the Aux input in my car?

So I'm currently having an issue and no matter where I look there's no answer online, which is rather frustrating. Firstly, I have a Ford F-150 Lariat 5.4 Triton. On the top of the radio it says "Line-In" where I'm able to plug in one of the Auxillary cord and the other end into my phone. On the radio, it has an Aux button. When I press it, it has three options labeled "Sat 1, Sat 2, Sat 3." Though, no matter what option I choose, no sound plays through the speakers and a message is displayed on the screen and says "Call Sirius" And displays their number. When I called them, they told me to buy a subscriton in order to "activate their services." So, does that mean I have to pay in order to even use the Aux or am I doing something wrong? I have an iPhone 8 Plus if that helps. The aux cord does work because I tried it in my mother's car and it works fine there.

Sirius is a satellite radio service. If you want to listen to them you need a satellite receiver and then you need to buy a subscription, I think it's around $10/month. Many newer cars have satellite receivers built into their radio but you don't have to pay for the service if you don't plan to listen to it.

AUX works exactly as you think. You plug in your phone and then pick the AUX input. Your radio might even have bluetooth, in which case you can hear your phone without even plugging it in. But if you tune your radio to Sirius, and you don't hear anything, that's because you don't have a subscription to Sirius.

Just rip the freaking radio out and put something better in that will give you what you want without all the hassle!

Your owners manual, which you have carelessly disregarded, explains what you can and can't do

Yes

Sirius was really in its infancy back in 2007 or so. Sirius was probably hooked to your Aux device and needs the subscription in order to make it work. Without that, the Aux button is useless. If you are trying to put your IPhone sound through the car speakers, you probably can't do it with the technology installed in that vehicle.
Remember that old technology doesn't play nice-nice with new technology-and they design it that way, so you keep buying the new stuff.

Try using another phone or change the aux cord and play around with the settings. If doesn't work get a after market one reasonable from Shopatronics, ect which would have around the same size to fit.

Take it into your dealer. Or a really good audio shop.

Aux in is not the same thing as line in. Look for the selection Line in in the settings.

Yes

Sounds like a bad connection