Hi Chris (@ccheltenham), Welcome to the LE community.
Network Solutions sells their own certificates - as shown by your apex domain of plspro.com. They do not give you root access, but will install a free LE cert for you for a charge (US$59.99?). With this hosting provider, whether you buy one of their certs or obtain a free LE cert, they are the one who will have to install it - for a charge. 
Here's two links, an older one and a fairly recent one discussing Network Solutions and LE certs.
You may want to switch to another hosting provider that allows you to install your own (LE) certificate. There's a long list of hosting providers at this link who support Lets Encrypt free certs.