On the nRF93M1 DK, the application you build is the host firmware for the nRF54L15 SoC.
The nRF93M1 module runs Nordic-maintained modem firmware that you do not build, so the nrf91-modem-trace-uart snippet used for the nRF91 Series does not apply.
For details, see Configuring and building with nRF93M1 DK in the nRF Connect SDK documentation.
When capturing the modem trace from the nRF93M1 DK, use the serial port of VCOM1, as described on the trace lte page.