Most parrots end up being one person birds. Yes an adult parrot can bond with you. As I posted before I got my previous B&G Macaw "JaJaBinks" (passed August 2020) from her previous owners who had gotten her at 5 months of age & then abused/neglected her. She was 2 years & 1 week old the day I got her. They couldn't handle her. She lunged, tried to bite & screamed a lot, so they kept her in the dark 24/7. Her vocabulary consisted of Hello, Whatz-up & Shut Up. In reality they had no idea how to handle a parrot & especially one that was going thru the terrible 2's. She had a tiny junky home made cage, a one inch dowel rod for a perch, no toys, no daily interaction & a bad diet of wild bird seed & peanuts. Not how you raise a macaw at all. I had no cage for her. Ordered one as soon as I got her home. We kept her in a large wire dog crate, with perches, food dishes & toys at night. During the day she was on a play gym. She came to me super filthy. Her back & wing feathers curled up in the air she was so dirty. Her toenails were at least 2 inches long. I stuck her in the tub & scrubbed her twice to get all the dirt off. She sliced the palm of my hand open with her long nails & screamed a lot. Then I clipped her nails. After clipping one nail she just held hr foot up for me to do the rest. One the way home with her I promised her she'd never be in the dark again & she'd have lots of good food & toys. After getting her all cleaned up I stuck her on the play gym & gave her a good meal. She went crazy she finally felt clean & well fed. She feared being touched & would run screaming in fear. In her mind that meant being hit or stuff in a small cage & put in the dark. She'd ACK so loud the nieghbors could hear her outside with all doors & windows closed. A macaw ACK goes right thru you it's so loud. It took 6 weeks for the cage to arrive. During that time I changed her name & worked with her daily to earn her trust. By the time the cage arrived I had taught her to step up/down. Yes I got nipped many times. She watched me assemble her cage, place perches & toys inside. I sat her on the door & let her explore it. She spend one more night in the dog crate. The next day we moved everything around & placed her new cage in front of a window. She loved her cage. She bonded to me & wouldn't let anyone else touch her in the almost 20 years I had her. I could rub her feet, stick my fingers in her mouth, peel her beak, etc. She quickly learned to go back to her cage on command. I could let her cage door open, as she would pretty much stay in or on her cage. She'd come looking for me. She loved helping with daily chores. I taught her to dance, wave her wing & say bye-bye, etc. She loved going to the Harley club & hearing the motorcycles fire up. She loved going for rides in the truck or just hanging out on our front porch. She'd yell hello to anyone that walked by. She LOVED Halloween & yelling at he kids. She'd scream & scared them then laugh. So as you can see you can take an adult & turn them into a wonderful companion. It takes time, patience & understanding. Other parrot owners have posted the same about the adult birds they got.
The 2 sites you posted above are scams. Red flags: Cheap prices, eggs for sale, etc. I found info on this site you posted:
Puppy Scammer List Website: Terryparrotfarm.com Scroll down to read posts by people that got scammed.
Some info on the other site you posted, again scoll down to read the posts of those that got scammed:
Macaw parrot eggs for sale 2021 Reports & Reviews - ScamPulse.com
Cheap parrots are far & few between. Unless you are able to find a person wanting to give up their bird for cheap & can go see it in person & take it home that day, you will get scammed. Unless you are able pay a honest breeder or parrot store the asking price for a bird you will get scammed.