Had a 30 min conversation with HR about my background. As others have stated, you must complete a coding challenge first. I provided them with a fully functioning project with expected output and unit tests. Unfortunately I wasn't able to move forward. Feedback was given and they are very critical of your programming style. Some good, some bad. Caution, anything in the instructions that say "optional" or "not required" is actually REQUIRED and a MUST HAVE...
Interview questions [1]
Question 1
They did not like that a "for" loop was being used instead of "foreach" even though they are identical in performance for the given context.