Understanding the Requirements for 'queries_df' in Evaluation Quickstart

Hello! I am following the evaluation quickstart, and I'm not so quick at it unfortunately. On the sample code in step 3, I'm wondering how to get a working queries_df . It says Assume 'queries_df' is your input dataframe for Q&A correctness , but what properties does this dataframe need? Step 2 works fine, and I've tried to run it with the trace_ds from step 2, but it fails spectacularly. Help please!