Download and install the most recent version of Write-N-Cite for Mac here: https://refworks.proquest.com/tools/ffw/
After installing, open Word 2011 for Mac and navigate to View>Toolbars and make sure that RefWorks is checked.
This will enable the following toolbar. Click on the login symbol to log in to either New RefWorks or Legacy RefWorks:
Earlier versions of Word may refer to New RefWorks as Flow. If this is the case, login to Flow.