Hi Sabrina,
welcome to the TonUINO project.
To enable the five buttons, you need to flash the appropriate firmware.
This easily can be done by using the Web-Uploader which allows selection of several configurations for best match with your hardware.
A little help may be getting some text tranlated by deepl.com. Simply copy the text and insert it on that webpage. I think you will receive quite acceptable translations.
For debugging purposes it is essential to see a copy of the log-file written to the terminal (console) when connected to your PC. The log will show your button presses and what is going on in the software.
This means you are almost there. The Software is running, the DF-Player is working and your SD-card is filled (almost) correctly (you hear the voice instructions and messages).
Last step to success can be done analysing the log output as mentioned above.
For more information please see (may help assisted by deepl.com ):