It can be confusing with this prophecy referring to both a teaching -- when the Buddha says "there is a teaching" -- and to the prophecy text itself, as in the quoted text in your question. "This spiritual text" refers to the prophecy itself. "There is a teaching" refers to the Surangama Sutra. The next question that might come to mind, is why doesn't the Buddha just say "Surangama Sutra" directly?

We have to remember that Jamyang Khyentse Chökyi Lodrö says that he collated this prophecy from earlier prophetic texts. This was at a time when the Surangama Sutra was being slandered by academics who didn't like the Buddha's disparaging of their academic learning. The Buddha is very clear in the Surangama Sutra that his teaching must be practiced, not memorized, for it to have any effect. So Chökyi Lodrö may have not named the teaching on purpose, so that the prophecy would not be similarly slandered before it could read by people, trusting that when the time came, someone would make the connection between this prophecy and the Surangama Sutra. And this is what has happened.

If you are interested in the history of the Surangama Sutra's slandering in Tibetan Buddhism by the academics, I have written an account of it: The Complete Instructions for the Practice of the Buddhas’ Secret Path. To access it, click on "Tradition" in the navigation bar, either below the picture at the top of this prophecy text, or and the bottom of it, and you'll see it listed after the Surangama Sutra.