Copying only an h file into your directory is *not* the proper way to install a library. You should list the library in the “lib_deps” section of your platformio.ini and run the command
pio lib install
which should install the libraries listed in that section and their dependencies or you can install a single library with the command
pio lib install xxx
replacing xxx with either the name of the library or the location of a git repository.
The most recent version of PlatformIO also has a point-and-click style (gui) library manager available through the platformio home menu. See this for more information on that: https://docs.platformio.org/en/latest/librarymanager/
I added screen shots of how you get to the home in Atom and VSCode.