Two Issues: Processing, not executing (I have the .env file) and How to change default code?

Hi!

Great work on the app. I'm having some problems in execution. 

I have made the RapidAPI key and created the .env file with correctly configured constants. However, it is still not compiling? Any suggestions?

Also, I can't find where the default code (the BST code that shows up upon initially running) is. I would like to change it. Where is it located? 

