Based on my childhood I would not suggest that you worry too deeply about it. Instruct her, but don’t make it a big deal. Like “don’t forget to say ty” vs “what do you say”. One comes off harsher and while autistics can be dense on somethings, not everything. Anxiety can be reinforced by having to much pressure on people in general. Autistics often need more time to adjust and adapt.

If you are a polite person she will learn by your example afterall.

I suspect my husband is autistic. He's in his late 30's and I've finally got him to understand why saying "please" and "thank you" is important, even if he isn't feeling like saying it at the time. Sometimes he still doesn't, but he does say it when he remembers to (unless he's focused on something else in which case it's "yes" "no" or silence if I ask if he would like something from the kitchen)

I think it's helped with his work relationships as well.

I think you're doing the right thing