You could email them? Use the email from the order email or in your orders list. Just send her the files. Buyers do not like to have to jump through hoops so make it easy on her and just email the files to her. Let her know in a separate email that you're sorry she was having so many problems and that you are sending them via email so it's easier for her. Let her know the next email will have the attachments so she knows to look for them and not spam the email over the attachments.
I looked at your shop to get an idea on how big the files would be and I don't see anything digital. Did you mean a different shop or did you word it wrong?
Either way, when it comes to digital, if the buyer can't access them, email is the next best option. Second best is to use a cloud like Google, iCould, Dropbox, etc. Then you can convo or email her or do both.
