Winona my pair (brother & sister) came from a feral colony and were a year old when trapped. They then spent another whole year at the rescue as nobody wanted 2 black cats who were extremely shy. They did what they could, but the rescue they came from is so full they couldn't really spend an awful lot of time getting them used to people.
That could be why the rescue said if you don't get on, you can return them. Feral cats take an awful lot more time to get used to any people around at all, and most people want house cats who are sociable and pet-able from the start.
3 days they hid under/behind the sofa, only coming out for food and the litter tray when I was in bed. Took me months before I could touch the bolder one, the girl. It took an awful lot of patience on my part when I desperately wanted to scoop them up & cuddle them, but had to go at their pace.
3.5 years down the line, they come dashing to the door when I come in. Girlcat takes treats from my hands, Boycat eats Dreamies from my body in bed. Neither sits on laps but both tolerate being picked up & even occasionally purr when I scritch their heads at the same time.
Girlcat likes to lie on the back of the sofa while I reach up & stroke her tummy or head, Boycat prefers to snuggle up next to me for that - I'm not allowed out of bed in the morning without him having cuddles!. They are still shy around other people, but both demand my company.