Unfortunately, the testing agency's first two options on the page where you schedule your exam list the reciprocity exams. Reciprocity exams are for "licensed" real estate agents from another state. Those individuals who want to obtain a Missouri license.
You must call PSI and explain to them that you have chosen the incorrect exam and that you are NOT an out-of-state licensee.
Hopefully, this issue will be corrected on the PSI website soon.