How to run "assess" that's inside my makefile?

As you can see in this GitHub repo, I downloaded a solution from NIST Random Number Generator Test Suite that contains a makefile and C files in the subdirectories.

According to pg 96 of the documentation provided, I have to run make and then run assess 100 (or any other number). I was able to successfully run make but I can't seem to run assess 100, as it just says "command not found". It's supposed to display this I believe:

I tried to go through this makefile tutorial but I wasn't able to understand what's going on. What do I do?

Here's the top snippet of the makefile, if it helps:

CC = /usr/bin/gcc
GCCFLAGS = -c -Wall
ROOTDIR = .
SRCDIR = $(ROOTDIR)/src
OBJDIR = $(ROOTDIR)/obj
VPATH  = src:obj:include

OBJ = $(OBJDIR)/assess.o $(OBJDIR)/frequency.o $(OBJDIR)/blockFrequency.o \
      $(OBJDIR)/cusum.o $(OBJDIR)/runs.o $(OBJDIR)/longestRunOfOnes.o \
      $(OBJDIR)/serial.o $(OBJDIR)/rank.o $(OBJDIR)/discreteFourierTransform.o \
      $(OBJDIR)/nonOverlappingTemplateMatchings.o \
      $(OBJDIR)/overlappingTemplateMatchings.o $(OBJDIR)/universal.o \
      $(OBJDIR)/approximateEntropy.o $(OBJDIR)/randomExcursions.o \
      $(OBJDIR)/randomExcursionsVariant.o $(OBJDIR)/linearComplexity.o \
      $(OBJDIR)/dfft.o $(OBJDIR)/cephes.o $(OBJDIR)/matrix.o \
      $(OBJDIR)/utilities.o $(OBJDIR)/generators.o $(OBJDIR)/genutils.o

assess: $(OBJ)
    $(CC) -o $@ $(OBJ) -lm

$(OBJDIR)/assess.o: $(SRCDIR)/assess.c defs.h decls.h utilities.h
    $(CC) -o $@ -c $(SRCDIR)/assess.c
...