ClubSport DD+ GT7 driver new in ACC - some questions

[wlashack]

Hello,
I have ClubSport DD+ base and the only racing game I have experiences with so far is GT7. Yesterday I tried ACC for the first time (on PS5), quickly picked a GT3 car (Lambo and Porsche) and tried Redbull Ring. I made several laps with each of these cars and it felt somehow strange to me in two aspects:

1. both cars felt like they weight nothing. Like I am driving a cardboard box.
2. both cars were performing heavy oversteer, like they have no grip

My question is — what am I doing wrong? Do I have to make some settings first to "feel the car"?

Thanks.