jadelson on "[Plugin: WordPress MU Domain Mapping] Domain Points Off of Wordpress Network"

Hopefully this summary is descriptive enough:
I created a Wordpress Multisite Network under MySite.com; domain and website is hosted via Dreamhost. I use a subdirectory structure for the network (e.g. mysite.com/site1, mysite.com/site2). I helped a family member start their own Wordpress site on GoDaddy; recently I transferred that domain to my Dreamhost account and would like to add their website to my Wordpress network since I help maintain their site.
I would like the URL to be companyname.com and not MySite.com/companyname.
When I try to map the wordpress company website to companyname.com it goes to a folder outside of my WP network and to a parked/staged website for holding.
I assume this is a simple mistake on my end, but I do not have enough experience with multisite networks and domain mapping to navigate out of this mess. Any ideas?

https://wordpress.org/plugins/wordpress-mu-domain-mapping/