In order to create lacto-fermented vegetables, you need whey in the liquid form, not the granules. I have no idea where you could buy whey. But I have an easy way to "extract" it.
32 oz carton of organic, plain, whole milk yogurt
2 large paper towels
Place the colander in the large bowl. Line the colander with a single paper towel. Pour the whole carton of yogurt into the colander. (Make sure the yogurt stays inside the paper towel.) Cover the yogurt with the second paper towel to keep it from drying out. Place everything into the refrigerator for 24 hours.
The whey will drip out of the yogurt. Check the bowl every few hours and empty the whey into a jar. This will keep the yogurt from sitting in the whey as it collects. After 24 hours, you can empty the strained yogurt into another paper-towel lined colander to keep extracting or you can put it back in its original container, depending on your preference for thick yogurt and your need for more whey.
You can use the yogurt as sour cream or just eat it plain. It's delicious!
The whey is now ready for use as a means of fermentation.