Hey Eliana! I have tried to explain the whole mechanism below. Step 1 is basically Friedel craft acylation of benzene by subsequent Clemenson's Reduction in step-2. In step 3, carboxylic acid is converted to acid halide. Then, again in step 4, it is an intramolecular Friedel-Craft alkylation. In last step it is simply nitration of aromatic ring using HNO3 in the presence of H2SO4.
Please feel free to ask if you find any question regarding mechanism.
Hope you find it helpful :-)