Problem

Domain name listed to select to install App.

Solution

Once you access to RVsitebuilder 7 of the domain name you want to install sitemap. Please go to website as admin, go to Manage app and click Sitemap. It will bring you to https://apps.rvsitebuilder.com/sitemap

1. Install app sitemap, and select domain name. Please see the attachment. 
If it doesn't list your domain, please open this link on browser by replacing your domain name on https://domainname.com

https://apps.rvsitebuilder.com/marketplace/urlnotify?siteurl=https://domainname.com

2. Click Generate once it's installed.

3. Follow this guide: https://support.google.com/webmasters/thread/16552944?hl=en

Your domain for sitemap will be:
https://domainname.com/sitemap.xml