Am I missing something with regards to acquiring a viynl group?

First off, I apologise if this is in the wrong forum. I’m asking for help, it’s to do with layers and shapes but also a kind of assistance in a technical way.

Having not played Forza since god knows what on the 360 (I took a sabbatical with GT6 for a good few years) I have come back to the series with 7. Whilst I think I understand that if I was to download a design for a car, as I have done with the Civic EK9 with a superb livery by JPT, that design is locked and can not be fettled with? This is fine for me, as it just looks the tits straight off.

I am personally trying to conjure up my own designs to start with, only simple ones mind, and noticed (for example) that in a thread or two JPT has said he has high quality logos to use, search his Gamertag or username to use them. So yesterday I have tried to find his vinyl packs with said logos but could only find the livery design for his Civic (as that is what I had to try the download feature out).

Is there something fundamentally wrong with how I am going about to search for the vinyl packs for individual logos that folk are sharing? I get that you have to have the car for a livery to show up, but I am going around in circles trying to find available logos. Probably much like you guy’s are reading this. If there is a kind soul out there that could explain to me in a real noob way, I would massively be thankful for that.

Cheers
TyHorse