I have installed and setup the Domain Mapping plugin

I have installed and setup the Domain Mapping plugin according to this article located here - https://premium.wpmudev.org/blog/offer-your-multisite-users-unique-domains-with-domain-mapping/

Everything was going good until I got to step #6. It instructs you to go to the new site/sub site and click on Tools>Domain Mapping. The problem is there is no "Domain Mapping" showing.

I have reviewed the earlier steps and believe I did everything right. Any ideas?