There are several possibilities. First, it is likely that they looked at your 2018 return and decided you didn’t qualify. So NEXT YEAR when you file your 2020 return, you can claim the $1200 against any taxes you owe. That is the most likely way this will be handled.
But at age 66 you might be on Social Security, so there is some small hope that your stimulus will still land there by direct deposit.