Token Caching Management in Actions getAccessToken doesn't exist?

I followed the code here:
Caching Management API Access Tokens in Login Action - Auth0 Community

However, this doesn’t work.

There is no management.getAccessToken() that I can find and I don’t see any comparable method.

Second, the code is just terrible, not defining a single management variable that gets assigned to, showing the user to essentially duplicate their API calls. I can deal with that part, but it should be cleaned up.

So, how do I get the access token that the management client retrieved for me to cache?