They haven't made a 64-bit version for the Pi yet, and Mathematica is not a menu option when you setup 64-bit Raspberry Pi OS. The traditional 32-bit version is

They haven't made a 64-bit version for the Pi yet, and Mathematica is not a menu option when you setup 64-bit Raspberry Pi OS. The traditional 32-bit version is installable on 64-bit Raspberry Pi OS if you enable packages for the armhf architecture. I wonder if anyone knows when the 64-bit version is coming? From Wolfram's point of view, keeping the binaries restricted to armhf might perhaps be taking the place of more onerous copy-protection or licensing features.