If she likes me, why is she acting like this?

I was recently told on good authority that a girl really likes me. I know her name but that's it. We were in one pretty big class last year and I did notice her looking at me a few times but we aren't in any classes this year. One of her friends recently told me, "she thinks you're really cute and likes you" and then said "don't tell her I told you that though". I was pretty thrilled to be honest. As luck would have it, the next day I was walking past the supermarket and she came out with a shopping bag, she saw me but my heart sank because she walked past with her eyes on the pavement. I'm ngl she looked like she'd seen a ghost. I was going to say hi, but she made off too quickly and then I literally saw her running away and up the steps to the block of flats she lives in. I already knew she lived there as it's a place loads of people live in and someone else I know lives in the same block and I saw her there a few months ago. It was really embarrassing to be honest. What am I supposed to do now, I really want to go out with someone but this sort of thing happens all the time, like I'm told someone likes me but it turns out they don't.

I was recently told on good authority that a girl really likes me. I know her name but that's it. We were in one pretty big class last year and I did notice her looking at me a few times but we aren't in any classes this year. One of her friends recently told me, "she thinks you're really cute and likes you" and then said "don't tell her I told you that though". I was pretty thrilled to be honest. As luck would have it, the next day I was walking past the supermarket and she came out with a shopping bag, she saw me but my heart sank because she walked past with her eyes on the pavement. I'm ngl she looked like she'd seen a ghost. I was going to say hi, but she made off too quickly and then I literally saw her running away and up the steps to the block of flats she lives in. I already knew she lived there as it's a place loads of people live in and someone else I know lives in the same block and I saw her there a few months ago. It was really embarrassing to be honest. What am I supposed to do now, I really want to go out with someone but this sort of thing happens all the time, like I'm told someone likes me but it turns out they don't.