I tried the latest version of IDA (the free version), and it didn't work. It seems that only a 64-bit version had been installed. My computer is 32-bit. Can IDA only run on 64-bit environment now? I've seen no announcement regarding such change.
Can IDA only run on 64-bit environment now?
Actually even paid license version of IDA runs on x64 only. The HexRays company provides limited support for 32 bit with a single goal - support for old 32bit plug-ins for old versions of the IDA.
In this case you have to use IDA Freeware 5.0 or something else, depending on your OS. For macOS and Linux good disassembler is Hopper Disassembler.
For downloading IDA Free 5.0 check this answer (same question with a problem of running on 32 bit OS): https://reverseengineering.stackexchange.com/questions/19179/older-versions-of-ida-free