Technika IV and later use a very common, and visually distinctive lens board. You’ll notice the they have the lower corners clipped. They’re used in Technikas, Technikardans, Shen Haos, Wistas, and other cameras. When I’m looking for lenses on eBay, I tend to gravitate towards ones that already have an attached Technika lens board, because it saves me time, effort, and sometimes cost.
If you’re buying a lens without the lens board you need, the first thing you need to determine is the shutter hole size. Some places like KEH list it (when listing used boards for sale) with an actual measurement, I.e. 35mm. But usually you’ll see it listed as “Copal 0” or “Compur 1” or similar. That’s because each shutter has a standard hole size. If the seller doesn’t mention what shutter is on the lens, you can do a couple things. First, you can look online to see if you can find out what shutter was normally sold on the lens—though be careful. Some lenses changed over the years, or it’s possible the lens was remounted in a new shutter. Fortunately Copal and Compur seemed to match sizes, so a Copal 0 and a Compur 0 are the same hole size (and I assume the same lens element mounts and spacing, but I’ve never really confirmed that.). You can also look at the pictures and use some visual clues to determine the shutter. The 00 and 0 shutters have the usual progression of shutter speeds your used to from smaller cameras. The 1’s usually top our at 1/400. The 3’s top out at 1/125.
the Caltar in your link looks like a Copal 0 to me, but I’m far from an expert. So you would probably need a Technika board drilled for a #0 shutter. You can look on eBay, and will find the from about $20-???? If you’re buying a board less lens, the other important thing to check is if the lens includes a retaining ring. This is required to mount the lens to the board rigidly. The shutter has a large diameter externally threaded shaft about the diameter of the hole on the board. It slides through the board and a threaded ring screws in from the back and clamps the board to the shutter. Then when that is tight, the rear lens element is screwed back into the rear of the shutter.
this is a quick overview from someone who is far from an expert, but others can chime in if I misstated anything.