Unfortunately I'm not knowledgeable in this subject of isolation so I am not able to advise on a solution other than the obvious ones of either not using the isolator (if it isn't actually required for the project), or using a different isolator that can supply more current. Hopefully the other forum helpers will be able to provide qualified advice.
You could power the system through a separate power supply. However, depending on the specifics of how the power is supplied, this could result in a loss of isolation.