This AP certainly has an Approach Mode. The trick is figuring out how to get to it. According to the linked manual it will automatically arm APR mode if a LOC frequency is set and then NAV mode is selected.
oops....what BigBen said...
You can also disable & re-enable GS arming (eg during a hold prior to the approach) by pressing & releasing the NAV button twice. Once re-intercepted the LOC then GS can be armed again by a further press of the NAV button. At least, that's what the manual seems to say. But then, it also says that pressing ALT when in ALT mode will also disable GS arming.
Frankly, I think it's a poor interface. I much prefer a discrete APR mode selector.