Since the Industrial Miner (Digital Miner) is a multi-block structure – this means that all the parts to craft it must be physically placed in the world as shown below. Note that the piston’s need to be placing up. If you’re having difficulty placing the chest on top of the dispenser, you can also use a shift click to make that a little easier.
After you’ve build the multi-block structure, you’ll need to place coal into the chest to act as a fuel source for the miner. After fueling the miner, just right click on the dispenser and the miner will get to work. You’ll see a bit of an animation and the chest will start to fill with resources.
The miner will only scan for resources and mine those blocks. Blocks like dirt, gravel, and stone will all remain untouched. As you can see in the image below, once piece of coal produces a fair amount of resources in a short amount of time.
You’ll also see a message in chat once your miner has finished, indicated the number of resources it mined.