In this example, Budget and Revenue are the only two measures in the crosstab - m1 and m2 respectively. Also, we have a Time dimension - on the month level - along the vertical axis of the crosstab.
The scenario is, that we are at the end of September 2021, looking back at the Revenue achieved so far, compared to Budget of the full year.
The two calculations, 'Acc Budget' and 'Acc Revenue' are both added as calculated columns to the crosstab.
sum(d1, d1:0, m1)
sum(d1, d1:0, m2)
In both calculations, the 'accumulation' comes from the row reference of 'd1:0' - which means that each calculated value is calculated as the sum 'from the first row to the current row'.
The line chart is a copy of the crosstab turned into a line chart. Furthermore, with the Visibility option from the Properties Smartpad, the two original measures have been made invisible (unchecked).