Portal Theme ....? What And Where Is Portal Theme?

Good-evening!

We have been looking for something to link our WordPress to WHMCS install. And when it seems we have found one, we saw this: "WHMCS Integration requires use of the Portal theme to function correctly".

Now I have been wondering what this special Portal theme is and where we can see it. I saw below:

http://www.demo.whmcsthemes.com/

but not sure if that is what it means.

Every WHMCS theme has the word Portal Home on it. Does it mean any theme with such word on it or just a specific one called Portal?

Thank You!