Maximum Trigger Current IFT
The maximum trigger current is the current at which the output triac is guaranteed to switch on. Your circuit must be designed to supply at least that much current.

The typical trigger current value is quite useless, because the chip that you actually have might have a higher value.

The internal IR LED behaves like any other LED; you have to use a resistor or some other current-limiting mechanism to ensure that it does not get fried.