On-Prem v2011 and later, MS CRM Cloud
After logging into Dynamics CRM, this is the first portion of the URL that displays in your browser's address bar. If your account is hosted by Dynamics 365, it is typically something like https://my-company.crm.dynamics.com/. If your CRM instance is hosted on-premises, it will contain a server name or a portion of your company's domain. If you aren't sure, ask your system administrator.
If your account is hosted by Dynamics 365, choose CRMOnline. If your CRM instance is hosted on-premises (by your own company), choose CRM2011+.
Internet Facing Deployment
This option is only used in some cases if your CRM instance is hosted on-premises (by your own company). If you aren't sure, leave it unchecked. If you're having trouble connecting to your instance, try checking it or ask your system administrator.