There is one other reason it stops at 5 secs that I forgot to mention...
At that exact point, you are required to enter your computer's user/system password... so Logic can actually install the additional content.
Note: This is not the same as your Apple ID Password though both passwords can actually be the same if you so chose to make them so.... or you used the option to use your Apple ID's password as the System/computer Password... when you set up your Mac initially.. but again, they don't have to be the same and so it's easy to get confused.
If you fail to notice this dialog box... cancel that request or type in the wrong password or fail to enter the password altogether.., the download/install sequence stops at exactly 5 seconds to go and cannot proceed...
Also, sometimes people either miss this dialog box asking for their computer's password... because they are using multiple screens or multiple spaces and either the popup dialog box asking for this password gets hidden behind another window or its on a different space or screen... or they cancel the dialog box because they don't realize why it is being requested.... which again causes this issue...