How long does this update take

You didn't say how long it seemed stuck. That's important to know. Normally, an update or upgrade download can take an hour, more or less, to complete. Then the installation can take another 45 minutes, more or less. Sometimes when doing a download of these very large files via Wi-Fi, there will be problems because Wi-Fi is much slower for these very large files. When that happens, you will need to do another download. If you continue using Wi-Fi, it make several attempts in order t get a clean file that will load successfully. If possible, it is better to use a direct wired Ethernet connection for these downloads.

You may need to install after starting up in safe mode.