Performance Calcuation

Hi gents,

Hope everyone is well. I require some assistance with regard to a performance calculation that would be greatly appreciated. I have a client who is trying to calculate their portfolio performance return and compare it to the benchmark index and the flows are as follows:

26/03/2013 +$612,231
03/03/2016 +$49,435
28/02/2017 +$47,187
03/03/2020 +$58,984

So only money put in, nothing taken out. The value at 15/07/2020 is $795,542.

The benchmark index value is as follows:

26/03/2013 42584
15/07/2020 45672

The client wants to calculate the performance of his investment vs that of the benchmark index from 26/03/2013 to 15/07/2020 but I find it very confusing with how far apart the initial investment is and the additions. I understand it would be the Money Weighted return used to do the comparison but I am struggling to grasp the calculation.

Thank you for the help.