OrangePi Zerro 2, using the UART at pin8 and pin10

[hazi]

I would like to use the uart of the orangepi zero 2 for an application. It esists for example /dev/ttyS5. But unfortunately the communication does not work. When I connect minicom to this port and short the two pins 8 and 10, I wanted to see the characters that are sent. Minicom can be connected (minicom -D /dev/ttyS5). But the characters are not mirrored. Do I need to enable the UART before? How to do this? The orangepi-config program does not exist on the system.
The system reports after the login with: Welcome to Orange Pi 3.0.6 Bullseye with Linux 5.16.17-sun50iw9
Thank you for your thoughts.