The MAX98090 has a USB audio input interface, and an S/PDIF input/output interface. The evaluation kit has IC switches onboard to route the appropriate I2S signal paths. These swithces can be configured to path the MAX98090 IC to one of the two interfaces or the other; but not both at the same time.
This is also displayed graphically on the evaluation kit GUI, where there are switches that you can click to route either the USB Audio or the S/PDIF paths. Both switches cannot be closed at the same time.