A power input is where you input power to a device. Connect your power source here. Examples include the 5V pin on the WeMOS, the VM pin on the TB6621FNG and the Vcc pin on the TB6621FNG.
A power output is what you find on a power source, power can come out. Such as the poles of your battery.
The Vcc pin of the WeMOS can be both power input (if you connect a 3.3V power supply here) or power output (if you connect a power supply to the 5V pin, or the USB connector).
I get guidance that takes me nowhere.
I was suggested to use a TB6612FNG instead of L293D or l298n, and then I end up in the same situation...dangling
I don't know why you're suggesting that the TB6612FNG is so much more complex than the L293D or L298N to use, as it isn't. The pin markings may be a bit different, but as long as you understand circuit basics and what those chips actually do, there should be no problem switching between the two.
Besides, there are heaps of TB6612FNG tutorials out there as well. Complete with wiring diagrams, example code, etc. No reason to duplicate those things here. We can help leading you to the water... but the drinking, you really have to do yourself.