It is certainly one of the biggest questions so not problem if is confusing. Read a few posts and you find most still have lots of questions and the answers are constantly changing!!
But on the clamp light, it is not necessary to have any special bulb for those lights--as long as it screws in and isn't too terribly hot so that it melts something.
And that brings around some suggestions. One is that LED run much cooler for the amount of light they put out. That light is rated to use up to a 150 watt bulb that can fry an egg at fifty feet! They do really use them to keep turtles, etc. warm.
But LED come more in 10 watt and I doubt that you can even buy one for 150 watt. Street lights, maybe? So feel free to use most any bulb you choose.
Second thought is that light may be way more expensive than needed. You may have reasons for choosing that like appearance, etc. but for value, this might be the same light:
For a ten, there may also be some real value in looking at CFL (twisty) bulbs as they are now be put out of use by LED. If you run across a tub full of CFL that put out light rated at 6500K (Kelvin) , they can sometimes be found for free. They work fine and all lighting does often take some looking and playing up and down before we settle on the best. For lighting, I love staying flexible and cheap with fixtures like this as it makes it simple to adjust with only needing to screw in more or different bulbs.
The old "gooseneck" floor lamps are real handy and cheap way to get something that moves up and down easy until you figure out how much and how close. I can find them for $3-10 at Goodwill.