For the Sitefinity's work there is no requirements for the number of the concurrent database connections. Basically it could work with only one connection.
The license that you will choose should be suitable to your expectations for all incoming requests at the same time. If you expect that the administrative part of the site will have high load you better have more CALs, because the database WRITE operation require more time to be executed, than READs. If the CAL are lower the connection to the server will be slower.
Hope this helps.
the Telerik team
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