Texts are not something you should have to download. Now multimedia messages (MMS) required downloading as they have more than just text in them.
If she is sending messages that include more than text in them (images, etc.) then ask her to send it to you without the attachments and you should get them. Also if she is sending from an app other than the phone's standard messaging app it could be sending the wrong type of message (MMS instead of SMS) which would cause problems as well.
However, as long as you have data on your device, you should be able to get the message and download whatever is attached, I would just make sure that she has attached something and was the sender. Many things will show up on a phone saying it is from...