I feel kinda stupid, as it has to be something simple.

I connect a single digit (and I tried 4-5 digits) to a constant combinator and select something like 167 iron ore. It only shows "0" no matter what I seem to select in the combinator.

Any suggestions?

Hello,

do the output of the combinator and the "action" input of the connected digit match?
To make the digits work, you must specify an action (i.e iron-plates > 0), this ist due to that the digits are technically a lamp.

If this doesn't help, can you provide a screenshot?

That was what I needed. Recommend that you give a basic example in the Information page on how to use. Thank you!