The article points to sciencedirect, which doesn't seem to offer access to the research paper without paying, but I could find the paper elsewhere:
<a href="https://ei.northwestern.edu/wp-content/uploads/2019/11/Manning_2019.pdf" rel="nofollow">https://ei.northwestern.edu/wp-content/uploads/2019/11/Manni...</a><p>> Among children who are
late talkers at 24 months, 40% qualify for a diagnosis of language disorder or impairment at school age