Making a dynamic queue of structures?

Question

https://code.sololearn.com/cl2M6MGitC2d/?ref=app

In my code I have a structure called Task, which represents values of a robot’s target velocities and positions. And then I have a Structure called Queue, which contains an array of Tasks and variables to keep track of the size(last element) and capacity of the array. But I can’t use the calloc and realloc functions, can someone help me solve the problem?