No action "Check Crossref DOIs"

What could it be a problem if I don’t see where to click “Check Crossref DOIs” on the Reference of Publication tab?
OJS current version: 3.3.0.8
Crossref Reference Linking v1.0.2.1 is installed.
The blue checkbox on the right is enable.
If I go to the Publication tab and References then I have “Save” button only.
Crossref DOIs is assigned to articles, article references are separately entered (but no idea what does it mean “extracted”). The article DOIs is deposited to Crossref.

The publishing section only defines the DOI.
For doi settings this video can help: How to Deposit DOIs to Crossref in OJS 3.3 - YouTube

This video does not explant how to use Crossref Reference Linking plugin for References. In fact I don’t understend this instruction for Docs Reference Linking and Deposit.

Where is it to click?