Hi Zygmunt,
you can take a look at this schematic, for example:
https://www.nxp.com/downloads/en/schematics/LITE5200EVALSCHEMATIC.zip
The clock should be connected to SYS_XTAL_IN while SYS_XTAL_OUT should be left floating.
And a note - this device is not recommended for new designs.
Regards,
Lukas