The 23/26ai VirtualBox Appliance has been retired, and is no longer being maintained nor is it available for download. I’m keeping this post active for anyone that may have already downloaded it and is looking for help.
You can download it here.
With this VirtualBox Appliance, you can spin up a virtual machine that already has Oracle Database, Application Express, REST Data Services, SQL Developer, SQLcl, and more…all running for you, automatically.

The APEX team has also given you a TON of new APEX 18.1 focused labs. Including one for using REST Enabled SQL from ORDS.

How to launch SQL Developer
In the terminal/console, run ‘sqldeveloper’
That’ll launch 18.1 for you.
Create a connection for ‘HR’, and remember, the passwords are all ‘oracle’
Don’t need a ‘big, fat GUI?’ Then just type ‘sql’ and you’ll be in our modern command line interface for the database.
Enjoy!