Hi @paulskirk53,
The PlatformIO project structure is reasonably mandatory, although src is where your main source file(s) are expected to be, you can change this using the src_dir = whatever where whatever is a folder, I think within, your project’s main folder. (I haven’t used a non-default structure, yet!)
If you don’t have src, or if there are no *.cpp files in it (or in whatever src_dir points to), nothing will compile.
A platformio.ini file is a necessity for a folder to be considered a PlatformIO project.
Further info on structure etc, by @maxgerhardt, on this thread
Oops! I’ve just noticed that’s your thread!
HTH
Cheers,
Norm.