There's an Add (+) button at the bottom of your screenshot. Click the Add button to add a new document type.

Do you have this information for reference? No, I do not. That is why I said in my first reply that I was guessing. Read the comment to my earlier answer from an Apple engineer. You must update to Xcode 13 to test your app on the iPad Mini 6.

My guess is Xcode 11.4 does not support iOS devices introduced after Xcode 11.4's release, which was March 24, 2020. The iPad Mini 6 came out in 2021. Do you have another iOS device introduced after March 2020 to test my guess? You most likely need to update to a newer Xcode version to install your app on the iPad Mini 6.

If you are writing lots of small programs for a C programming course, you are better off using a text editor like VSCode, Sublime Text, BBEdit, or TextMate to write your code instead of Xcode. Xcode requires a project to create an executable file. You can't just create a C file in Xcode and run it. I know TextMate has a C bundle that lets you run your programs from inside TextMate by choosing Bundle > C > Run. I'm sure the other text editors I mentioned have ways to run your programs from the editor.