Unfortunately, she committed a crime.
Trespassing. The store doesn't wanna be liable for her potential injuries or for damages to the property. Also, they don't know if one day she may break inside the store from the rooftop.
There's plenty of homeless shelters and social service programs she could've sought out.
DSS gives rent vouchers for the homeless to find a place to stay, whether that be in a shelter or an apartment. They'd also help her find a job if she's mentally and physically capable of obtaining and maintaining one.