There is no import file for Crows_foot.graphmlz - that sample was created manually in yEd.
Maybe there is a misunderstanding what yEd is and what yEd is not. yEd is an editor for diagrams. Its main purpose is manual diagram creation. Excel import is just a small convenience feature. Not each and every diagram that can be created in yEd can be created through Excel import (or Excel import alone).
That said, if you want to create an ERD diagram from spreadsheet data you have two options.
In yEd's palette, double-click the ERD entity node to make it the default node style. On tab "Presentation" of the Excel import settings, set option "Template" in section "Nodes" to "Selected Template from Palette". Additionally, create properties mapper configuration that extracts the attributes data from cutom properties and writes it to the ERD entity node's second label.
After importing your spreadsheet data, create a properties mapper configuration that replaces the default node styles with the ERD entity node style and extracts the attributes data from cutom properties and writes it to the ERD entity node's second label.
Note, for this to work, all the attributes data for a single entity has to be available in one cell in the spreadsheet because yEd's properties mapper is not able to combine data from multiple custom properties in a single label.