Azure Sql Database Pricing Calculator

I am trying to get an estimate for what it will cost to migrate to Azure Sql Database.  We are interested in either the vCore or DTU Elastic Pool Business Critical model. The estimate calculates a price per instance. My question is, under that one Azure Sql Database "quoted instance" can I create as many databases as I want? We have several clients (25) that we keep in separate databases.  What about our dev/test environment? Do we need to buy a separate instance for dev/test? If so, where do I get a quote for that?

Link to pricing calculator is below

https://azure.microsoft.com/en-us/pricing/calculator/