Okay, I tried using a conformal mesh with shared topology at the geometry level. After importing the geometry to fluent meshing, I managed to generate the volume mesh with a conformal mesh (see pic below). It consists of 1 object and 2 cell zones (And 9 face zones). When clicking on the button for switching to Fluent Solution it gets stuck at some point and it says that 2 zones are missing ("WARNING: Current Mesh is incompatible with mesh operations defined. Following zones are missing: ..."). Those are the 2 spherical surfaces touching each other which are now connected via shared topology at the geometry level. Since it's my first time dealing with shared topology, especially at the geometry level, I am a little lost about what went wrong...
You are navigating away from the AIS Discovery experience
