Problem building

[jirikeller]

As project does not have a graddle, I tried the approached described in README, importing from github in my Android Studio 3.1.3, target API 25. Import with everything kept on default, building own graddle.

While trying to compile, I get this error:

Unsupported Modules Detected: Compilation is not supported for following modules: main. Unfortunately you can't have non-Gradle Java modules and Android-Gradle modules in one project.

Can anyone point me to more detailed compilation manual ? I am a complete newbee in Android development - after compiling Saiy from the sources and confirming successfull build, I would like to change the TTS language to Czech (first step) and voice recognition language (and recognition strings) to Czech as well (second and third step ;-)) . Any help appreciated.

Thanks
Jiří