Key-based cache not available for free plan?

Currently I’m building my pipeline and it costs me a thousand year to complete so I dive into the documentation and try to implement caching strategy.

On Github Step’s repository have said that the key-based steps are on beta version and everyone can use it freely. But my pipeline outputs does not say so.

cache upload failed: failed to get upload URL: HTTP 403: {"message":"Unfortunately, this step is not available on your current pricing plan. Please get in touch with us to resolve this."}

and

download failed: failed to get download URL: HTTP 403: {"message":"Unfortunately, this step is not available on your current pricing plan. Please get in touch with us to resolve this."}

I also found a same question and it was already resolved: Key based cache not available for free plans?

Can someone help me take a look?
My organization slug: 77a3a68762f5fc65#. Thank you all!