Setup with 15 regions is being used in a single-region analysis type

I have encountered this error, I’m new to CFD please help
A setup with 15 regions is being used in a single-region analysis type. Please make sure that all regions except for one have an Advanced Concept assigned to them

https://www.simscale.com/projects/nvisser/case_study_5/

Hello, and thank you for using the Forum.

Once you created the flow region, please proceed to delete solid bodies in your geometry since solid parts will not be used in an Incompressible simulation. You will only need the boundary faces of these solids.

Hope this helps.