Crosby Fitzgerald wasn’t sure if she could live up to the Caroline Ingalls she’d grown up imagining.

The actress, 36, plays the beloved matriarch in Netflix’s Little House on the Prairie, an adaptation of Laura Ingalls Wilder’s semi-autobiographical books, and she tells PEOPLE that she had doubts about her ability to play the character when she first got the audition.

“I read Little House on the Prairie, and I’ve read all the books. My mom’s a huge fan of the books, my stepmom, huge fan of the show,” Fitzgerald says.

She was interested right off the bat by the audition, “and then I saw which character I was reading for Caroline — Ma — and I was like, ‘No, wait a minute. Hold on. I don’t know….’ ”

Based on how she knew the character from the books, Fitzgerald thought, “I’m not sure that I can [play] this person.”

“I consider myself sort of brash and loud and annoying, and she’s so poised and elegant, from what I remember from the books.”

“Then I read the script and I was like, oh my God, I really am in love with this person,” she says.

Showrunner Rebecca Sonnenshine and executive producer Joy Gorman did an “amazing” job breathing new life into the character, Fitzgerald says.

“These are all women who grew up reading these books and really saw themselves as little girls in Laura and then grew up with the books and then saw themselves in parts of Ma and parts of Pa and all of the characters that are part of the show.”

“I was just so impressed with how layered she was and fierce and still very grounded and still very poised under pressure,” Fitzgerald says of her character. “I was like, wait, she forges this river and then breaks her foot, all while she’s pregnant and doing this on her own. She pulls a shotgun on a wolf. I was just like, okay, I can maybe do this person.”

When she found out she got the role, “I just fell to my knees and started crying,” she admits. “[It] changed my life pretty much.”

Luke Bracey, who plays Pa, had a wholly different process being cast in the series. “When I auditioned for Charles, I was really unaware of what I was auditioning for. I had no concept of Little House on the Prairie,” he tells PEOPLE.

“[I] was able to come into this role, in this show, fresh. I didn’t have any preconceived notions of who he was or what the story was,” he said.

He said he knew Fitzgerald was the right actress for Ma “from the get-go” during the chemistry reads. “I really wanted it to be her,” he said.

“We became fast, fast friends and really fantastic teammates,” Bracey, 37, said. “I feel so fortunate that Crosby plays Caroline and that she’s my teammate through all of this, because it’s just a joy to go to work with her, and it’s wonderful to know that someone has got you back through all of this.”

He added, “I couldn’t ask for a better Caroline.”

Little House on the Prairie is now streaming on Netflix.