Why is a download of Catalina hanging?

There are factors:

1 - Like poor Wifi connection

2 - Slow wifi connection

3 - Too many other people downloading at the same time and Apple Severs are overloaded

4 - Software on the computer interfering with the download process including AntiVirus Software

5 - Running behind a VPN which may increase Packet losses and may even corrupt the download.

6 - If via wifi too many Other devices using the wifi at the same time reducing the Bandwidth to your computer. 

7 - Best Results are via Ethernet Cable to Router

8 - Any Third Party Applications that will interfere with the normal operation of the OS, alter, modify, remove or delete or attempt to do so is an invitation for disaster and may require a Reinstallation of the OS.

Any of the below should be removed as per Developers Instructions 

This includes AntiVirus, Disk Cleaners, Disk Optimizes, UnInstaller etc.There are no known Windows-like Viruses in the wild that self replicate and affect macOS, because of the underling UNIX  Foundation and Permission Limitation. 

The Only thing this Antivirus software is protecting is the Bank Account of the Developers and for zero return to the User aside from the problems this software creates.

The The Built in Security  is all that is required to protect the computer.

To perform this action will require booting from a Bootable Installer. 

This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of Catalina would have to be done on a computer that Qualifies to run Catalina .

If the computer being used to download the Full Version os Catalina id TOO NEW or TOO Old to run Catalina even if to create a Bootable Installer - this computer is Disqualified to perform this action.

The Apple " Licence of Use Agreement " prohibits downgrading to a version of maCO older than what this computer Originally came installed with.

Empty Space - it is suggested to keep at least 15% to 20% of the Drive Total Capacity as Empty Space for good operations of the computer and for additional updates upgrades to download, expand and install.

If this computer doesn't not have the suggest Empty Space Available >>

What is “Other” storage on a Mac, and how can I clean it out?

In Monterey the “Other “ category is named “ System Storage “.

Free up storage space on your Mac

OmniDiskSweeper Safe to use

GrandPerspective 

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See used and available storage space on your Mac

Locate backups of your iPhone, iPad, and iPod touch

The final word from Apple on Managing the " Other " Category

Other: Contains files that don’t fall into the categories listed here. This category primarily includes files and data used by the system, such as log files, caches, VM files, and other runtime system resources. Also included are temporary files, fonts, app support files, and plug-ins. You can't manage the contents of this category. The contents are managed by macOS, and the category varies in size depending on the current state of your Mac.

Hi,

How long are you waiting? I'd give it at least an hour to see if it finishes.