Hi,
From what I understand, the modulo N used in the figure is just a depiction of the operation required.
You can use a constant block having the value of N instead of the Modulo-N block, and then use a MATLAB Function block to perform the Modulo N operations as desired.
Attached below is a screenshot of the same:
Please refer to the MathWorks documentation links below to know more about constant block, MATLAB Function block, and the mod function: