Atlaskit editor plugin extension

Hi all.

We are looking for how to develop our own plugin for the rich text editor in Atlaskit.

We have tried to ready the development environment by either npm or clone source from here

Refer to the package.json, it requires "@atlaskit/editor-test-helpers": "^15.3.0"
npm found the old version 9.11.13

How can we solve?

Any comments are welcome.