Sounds like you need to activate. However, it doesn’t make sense why 9 would not work but 8 would.
Did you do anything else to the computer between removing 9 and installing 8?
I would reset the preferences and try version 9 again. Version 8 is running an old API the Adobe is not supporting anymore and it may not even load into CC 2023. Adobe hasn’t announce yet if that old API will be supported in CC 2023 or not. So probably best to figure out what is going on with version 9.