Sitecore is not available in the drop down list of source types in Source mapped to collections
Sitecore connector should be given as source type to crawl the sitecore contents. But in source type or allowed sources in a free licence Sitecore is not available.It is listed in the denied sources. How to add that to the allowed sources.
The Coveo for Sitecore free version includes the Queue crawler, which is the main connector for Coveo for Sitecore. The Sitecore connector is the older version used to crawl Sitecore instances 6 and lower.
Remember that using Coveo for Sitecore, you do not need to create anything in Coveo. Everything is managed within Sitecore.