Assuming that your data was imported into the correct format for AbsoluteCorrelationFunction, then AbsoluteCorrelationFunction is returning a list of data. So you'd need to use ListPlot. Plot is for functions or an explicit variable, hence the error message. E.g., your Listplot call would be
ListPlot[r, AxesOrigin -> {0, 0}, PlotRange -> All]
without your specific data I cannot be sure this will work, but give it a try.
