Flosum is a complete end-to-end release management and continuous integration application built from the ground up for the Salesforce platform. Flosum is 100% built on the Salesforce platform; it does not use Heroku or AWS in the back end.
The following diagram shows the architecture of Flosum.
In the above example, the Flosum application is installed in a separate enterprise-edition org that connects to your production org as well as development and test sandboxes. One Flosum org can connect to multiple different production orgs.
The Flosum org itself is an enterprise-edition org (not a sandbox) supplied by the Flosum team. (You do not have to contact Salesforce to procure this new org.) Alternatively, you can install Flosum directly in your existing production org.
A brief not on security: Although we refer to it as “Flosum Org” in the above diagram, the org is completely owned and maintained by you. No one from Flosum will ever have access to your org – it is completely dedicated for your use. Your team will have full System Admin-level access to your org.
Because the Flosum org is an enterprise-edition org, it comes with 25 developer sandboxes and one full data sandbox. More information about enterprise-edition orgs can be found here: https://help.salesforce.com/articleView?id=overview_limits_general.htm&type=5