How to extension dev

Ok. It now worked. There were spaces. I copy-pasted the commands from the 1st post which contained spaces :man_facepalming:

Step 9
I don't understand what to do here, he opens a black window but waits for the command. What do I need to enter there?

The description says what you need to write...

$ ant extensions

bash: ant: command not found

You have not installed ant.

You have not completed step 5 or 7. All steps must be followed carefully.