So the answer from tech support, for anyone else who may have been confused, is that you must also run 64-bit SAS for CST v1.5 to be able to be installed.
2025 SAS Hackathon: There is still time!
Good news: We've extended SAS Hackathon registration until Sept. 12, so you still have time to be part of our biggest event yet – our five-year anniversary!