about 4 years
ago -
Avanya
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Direct link
Assuming we're talking about the Industries DLC, that unlocks with the Tiny Town milestone (360 citizens). Then you will need to paint in an industrial area to unlock the buildings. That's done very similar to making a district, only you use the area tool instead. Here's an image showing which one you need to use to make an industrial area for the new stuff.
https://i.imgur.com/3Nv77k6.jpg
https://i.imgur.com/3Nv77k6.jpg