You can run mysql on any other free database on the 2 free compute instances. It is totally up to you. The autonomous database is Oracle's offering of their Or

You can run mysql on any other free database on the 2 free compute instances. It is totally up to you. The autonomous database is Oracle's offering of their Oracle database - that requires no DBA or tuning and runs on Exadata infrastructure. They are offering it for free - because they want enterprises using existing on-premise Oracle databases, to move their existing DB applications to the cloud. Oracle Autonomous databases comes with free Oracle APEX - which is a low code / no code toolchain.