Unfortunately your company has the expectation on you because you are employed. If you are not able to meet the deadlines, you are not qualified for your job. That's the whole point for probation.
Your company has the rights to fire you and hire another programmer who will do better job than you.
This read more like a comment, and did not answer the question, which was: "How should I professionally communicate to my manager that the issues with the code may cause me to miss the deadline?"
I posted a comment on the answer pointing this out (I deleted the comment later), and the answer was subsequently edited to include the below additional paragraph:
You don't communicate or negotiate with your manager. No excuse. You work on it professionally and do the best you can. Work very very hard. You do exactly you were told. Do it or leave the job.
The flag has since been marked as disputed.
Is this because when a moderator saw the flag, they were presented with the updated version (which did include an answer)?
Note: I don't really mind if the flag was "wrongly" marked as disputed. I am just interested in improving my understanding of the rules and how the system works.