I landed my first Upwork job last week (YAY!!) but the company did not hit the "hire" button until today (Tuesday). I need to go in and manually add the hours from last week. It doesnt look like I am able to do that, so I need to add them on to this week? Neither of the apps allow me to do this. I get a "You cannot add manual time for the time period you've specified"
Congrats on your first job.
You can't add time prior to when the contract starts, so you'll need to add it for a time period after the start of the contract in order to get paid for it.
A few things to keep in mind:
Manual time isn't covered by Upwork's payment protection, and the company's not obligated to pay you for time from before the contract started. Hopefully, you'll get paid. But, you may not.
You shouldn't start work before you're officially hired on a project.
If you haven't done so, I suggest you read through the material in the getting started thread pinned at the top of this forum.