Deductions & credits

I had an HDHP from January 1st, 2024, until October 31st, 2024. Since I was enrolled in an HDHP for part of the year, I was wondering if I can make a prorated catch-up contribution for the months I had coverage, or if there are other rules that apply.

This is what IRS says:

"When To Contribute

You can make contributions to your HSA for 2024 through April 15, 2025. If you fail to be an eligible individual during 2024, you can still make contributions through April 15, 2025, for the months you were an eligible individual."

Am I missing something ?