You can't download the software update without wifi. I know it's a stupid thing that Samsung did. I don't have a dedicated internet source, so I use my phone to create a hotspot to connect my computer to.
Knowing this, I got creative. I connected my desktop to the internet through my S10+ hotspot. I then turned my desktop into mobile hotspot to share my wifi back to my phone. It worked!
Go to settings, then click mobile hotspot. Next, turn on the mobile hotspot option. Now click edit, name it something, and put in a password.
Now go to your phone and turn on wifi. It will see your computer as a wifi source. Click on it and put in your password. You are now connected to a wifi network.
Congratulations, you have just downloaded your updates, and fooled your phone.