We had the hardest time with Starr before I found out what to do. Hopefully this will work as well for you, Coach is my fave and I'd love to see you get that bag for Christmas
Leave the bag on the floor, unzipped. Put a favorite treat in there. Let her go in there on her own. It may take a few days. Once she's going in there on her own let her do that for a few days. Then, start picking the bag up and just carry her around the house a little, with it unzipped, watching to make sure she doesn't jump out. Then sit the bag down and let her hop out. Do that for a few days. Then try zipping the bag and letting her hang her head out, and use the harness clip in there. Then after a few days of that, graduate to having the whole thing zipped up, and reward her with a treat when she sits in it quietly. She'll get the hang of and and even look forward to it once she realizes that she's going to get to go bye-bye with Mommy in it
Just take it slowly, and one step at a time. Of course she freaked out, she'd never been in a carrier before, right? Poor thing

A full day of shopping might be too much at first, just try short errands at first, that way if she's not doing well, you can take her home.
Good luck

I hope this helped a little