since I can’t give you a direct solution without access to the application, here’s the general idea how to get it done:
First, you will have to get to the correct month in the calendar.
What I would do there is getting the number of clicks required on the left or the right arrow, by figuring out how much bigger or lower the desired Month is from the current month. As I can see in the picture, the arrows change both month and year at the same time, so this will make it easier.
Then when you know how many times you have to click on one of the arrows, add an If statement to decide on which arrow to click, then a For loop to click on the desired arrow the correct amount of times.
Then, when you are on the correct month (you can make a check if the text above the calander fits), you will use selectors, with variables in them, to select the correct day. So the exact day that you will click on will be a dynamic selector and you will put the value of the desired day in it. So that’s how you will click on the right day.
Hope this helps you out, and if you want more exact help, let me know