If you want the unit to appear at the spawner/any unit, the triggers shud look something like this:
First you must create a location, place it anywhere, and call it 'Spawner' (or whatever you wanna call it).
Condition:
Always
Action:
Center location labeled 'Spawner' on 'Unit' owned by 'Player' at 'Anywhere'.
Preserve trigger.
Now you've centered the location on the spawner.
Then:
Condition:
Always. (I don't know when you want the unit to appear at the spawner, so you don't have to use 'Always'.)
Action:
Create 1 'Unit' at 'Spawner' for 'Player'.
Now you've created 1 unit at the location you centered on your spawner. I hope this is what you ment.