It seems like the difficulty you are facing is related to getting started with Bela, understanding the way it is designed to be used. If my guess is correct, then below might help you get the code running.
This first statement is to describe the assumption I am making about which Zip file you are talking about. The way to get a Zip file from the github repository I sent in a link is like this,
,then there will be an option "Code" and "Download Zip".
Is that the Zip file to which you have made reference?
If this is what you mean, then you may unzip this zip file you will have a directory structure of the repository, which looks like the corresponding github page -- within there are multiple directories each having a different sketch. Each one is its own Bela project and I am uncertain what Bela would do with the whole of Bela_Misc copied to a single project directory.
You need a new project that includes all the .cpp, .h and .txt files you see here:
This means on our PC you would browse to the kingon_tone directory under the unzipped Bela_Misc directory and upload those files to a new project from the Bela IDE, like below.
1) Download Bela_Misc repository zip from https://github.com/transmogrifox/Bela_Misc
2) Extract zip to your PC
3) Open web browser to Bela IDE -> create new project, name it whatever you want
4) Delete the default (auto-generated) render.cpp
5) Use menu option to upload project files
6) Browse to extracted zip directory, klingon_tone
7) Upload all .cpp, .h, .txt files from directory klingon_tone to this new project directory
8) Build and run
9) If 8 works, then you can modify code using the IDE editor to observe how it may change the sound, and/or adjust project settings in the IDE (e.g AGC gain, DAC gain). Defaults will be ok for testing basic compilation and verify sound has changed.
If you have more experience with Bela, there are more elegant ways you can learn to copy the code to the correct place The above method is one way that is easy to explain, and it works.