The datasheet states the G3R-ODX02SN 5-24VDC, which is an output module, has 8mA maximum input current consumption, but its load switching capability is 0.01 to 2A with an 8A inrush capability.
So 8mA is the maximum current needed to switch the SSR on, not how much it can switch (which is max 2A continuous 8A (10ms ) inrush).