With every created Report Definition you have the option to write an out-file (Report File) which can be post-processed using Third-Party tools or even manipulated within Python.
In Ansys CFD Post you need to create the Volumetric Flow Rate out of MassFlow Rate or using some solution variables: Are Integral of the velocity at the boundary Of interest. You need then to create a transient chart to show that volumetric flow rate vs time.
I recommend to stick to quantitivve evaluation in Ansys Fluent and rely on post-processing the outfile elsewhere. You have the Option in Ansys Fluent to show the Report Definition under Data Sources.