A scan profile can be a domain, subdomain or IP address you own. The great thing about scan profiles is that you customize them with different configurations so, for example, you can scan the same domain with different credentials.
Keep in mind, if you set a domain as a scan profile and there is a specific subdomain that you’d like to scan which is not accessible via crawling, it must be set as its own subdomain. This means that you may have multiple scan profiles for a domain depending on what and how you’d like to scan. See this video on how to add a scan profile:
Add a Scan profile