Before you can upload any of your (meta)data files to the platform, you need to tell the platform how your data is structured. For example, you need to tell the platform where the ID is stored, which properties you want to include, the data type of each property, etc. .

This can be done through the web UI, but also by uploading a data properties file which describes your data.

This data properties file is a .csv file where each row specifies what kind of data a property in your data files contains.

The contents and syntax is documented here.