Sorry the timing was confusing for you.
There are 3 additional hours available after signup ends to play games. A long window to finish games after signups have closed unfortunately would not be of much help, as without signups open there would be few people for you to play against.
I would encourage you to reach out to the Game Support team and explain your situation to them: https://mtgarena-support.wizards.com/hc/en-us