Install library for arduino using library manager

I managed to install some libraries for arduino project using the library manager of platformio. However for some library such as TTS.h ( text to speech), the library manager returns a reply as"Not Found".
Is there a way to install the libraries using the manager. Thanks.

I would like to extend this to ask if someone can create a tutorial about uploading libraries.
I have not found the library manager too useful and I have a lot of libraries on my PC that I want to drop into the global folder.
some are ZIP, others not.

I’ve just added this library to our repository. See PlatformIO Registry

Next time you can use in your platformio.ini

[env:....]
lib_deps =
  https://github.com/jscrane/TTS.git

See