Unless I misunderstand your comments, you are experiencing two issues - 1) problems saving and reopening SL projects; 2) updating SL to the current version.
For the first issue, I would verify that there are no components of the story file that are being called from a shared network location (Teams channel, OneDrive/Sharepoint site, network server). Storyline does not like to share resources over any type of network, so make sure that you are working from your local drive (C:\Documents\My Articulate Projects).
I would also confirm that all your Windows updates are current; I know that MS is putting Win10 out to pasture permanently, and if you are still using Win10 I would not be surprised to see this type of behavior, though it's a bit unusual to only see it with Articulate.
Check your computer memory and RAM health, as well.
If none of these resolve your problem, you are better off opening a support ticket with Articulate given your deadline. They can also help you with your apparent second issue.
Good luck -
