https://www.bunnings.co.nz/moda-35cm-granite-square-self-watering-stone-lite-planter_p2941337

I bought this planter for indoor plants but can't figure out how to use it, and cannot find any information online either. The outer part has no external openings, other than the raised spout in the base (there's a stopper provided under the tape in the photo). The inner is like a shelf with various depressions.
I have seen online that other similar planters have some sort of a spout and/or indicator for watering. If I put the stopper in (which I will have to do for inside use) the water will accumulate inside the container. If the plant and soil fill the top section, there is no way to tell how high the water level is. I could easily overwater without realising and kill the plant. There's no handle or anything to lift the plant shelf.
Mostly I have my indoor plants in a plastic pot which is placed in a solid cover pot, and I can lift the plant out to check the water level. But some are getting big and bulky and I had hoped the self-watering system would fix the problem. Would really appreciate any help, otherwise I will have to return the pot and go back to Plan A
Thanks