From the data sheet:
"Output capacitance: An output capacitor of at least
100uF with an ESR of ~50mOhms is recommended to damp Note that all control signals are referenced to Vsense-, which
the resonance of the output filter. More capacitance can be in this arrangement is at -Vout potential.
added to improve dynamic response to load variation; there
is no upper limit on the value of the output capacitance.
Very large output capacitors may slow the converter's start
up time due to the current required to charge them being
limited by current limit or Isetpoint."
and:
Input filtering: These modules should be connected to a Vin+ +Vin +Vout Vin-,Vout+
low-impedance source. A highly inductive source can affect Cin1 HVNQ Vsense+ Cout
the stability of the module. An input capacitor must be placed On/Off DC-DC Vset
adjacent to the input pins of the module to minimize input Converter Rvset
Vsense-
ripple voltage and ensure stability. See SynQor's application -Vin -Vout
note titled Input System Stability for guidance on selecting Vout-
appropriate input filter elements.
https://www.synqor.com/documents/appnotes/appnt_System_Instability.pdf