How to add follow author function on muti-user based WordPress site?

I fount this page but couldn't get it to work or understand how he got this working.

Making Wordpress author follow button, need missing ingredient

Any advice?

thank you!

How to add follow author function on muti-user based WordPress site?

I fount this page but couldn't get it to work or understand how he got this working.

Making Wordpress author follow button, need missing ingredient

Any advice?

thank you!