I had the same problem. I was using StrapiV4 instead of version 3, like in the tutorial. The problem is that the query to retrieve the data, doesn’t work using Strapi v4.
I solved this by using the command “npx create-strapi-app@3.6.9 BackEnd --quickstart --no-run”.
Hope someone can fix this for version 4 of Strapi, but meanwhile you can use this version that works perfectly.