I need help creating a retention chart

I am trying to do an analysis to show users who came back to make 100 api calls after the making their first 100 api calls. For more clearity, "100 api calls" is a key activation metric for us.

The way I plan going through this is to use a line + grouped bar chart where I'll have the 100th api call date as the X axis and the Count of Users on the Y axis. However, the challenge is in defining one or more series that I can use to breakdown the data to show the number/percentage of users in each of the monthly cohorts who returned to make another 100 api calls after 30days, 60days, 90days, 120days in percentages. I'm not sure what beast mode calculations to make to obtain that data.

I was trying to follow this video https://www.youtube.com/watch?v=5pTsFXJjIrY but got stuck defining the series and beastmode since that wasn't explained in the video.

ANY HELP PLEASE ?