Hi Antonio Pérez Laguarda
There is an example code of ftm_perioduc_interrupt in the SDK of the S32DS, you can use this code as reference and add the lines needed for the ftm_pwm example code also included in the SDK. you need to check the CHIE bit in the reference manual.
FTM_DRV_EnableInterrupts(INST_FLEXTIMER_PWM1, FTM_CHANNEL0_INT_ENABLE | FTM_CHANNEL1_INT_ENABLE);
INT_SYS_InstallHandler(FTM0_Ch0_Ch1_IRQn, &ftmTimerISR, (isr_t*) 0);
INT_SYS_EnableIRQ(FTM0_Ch0_Ch1_IRQn);
Hope this helps
Best regards