LP-CC1312R7: What program whas used to design it?

Hello,

I´m in the process of designing a device based on the CC1312R7 but before switching to the final prototype I would like to design a daugther board for the  LP-CC1312R7 and check that all the funcionality works fine before starting final PCB design.

I´ve downloaded the design files and there are 3 files in CAD Source (.BRD, .DSN and . opj) but i dont find any way to open or import them into altium, what program was used? in order to import or convert the files for use in this project.