Double bracket missing in Oracle Linux

So I was trying to write a script in an Oracle Linux server and nothing worked. To begin with, there is no double bracket as far as I can tell.

Also, the error messages I get are weird. For instance, this code :

[[ -f 'fake' ]] || { echo "There is a missing file"; } ;

Throws :

Bash : echo not found

I clearly understand the difference between the distribution and the shell you are interacting with, which makes the issue more weird.

I am a long life Centos/Ubuntu scripter so this experience has really been a bummer.

Can someone elaborate any other differences I Should be aware in this new environment?