The Sims 4 won't install. Stuck on 73% finalizing

@m1dnight2x  Please download Revo Uninstaller (the free version is fine) and see whether it detects Sims 4.  If it does, use Revo to uninstall it, and restart your computer.  Either way, use Revo to uninstall the EA App as well.

Reinstall the App, and create a new folder on the root level of the drive of your choice, for example C:\Games is fine, but not C:\Program Files\Games.  Install Sims 4 into that new folder.

If this doesn't help, please let me know what antivirus you use.

I uninstalled it all then reinstalled the ea app and I keep on trying to install the game on an external hard drive where I have more space, but nope... it's stuck...I use Malwarebytes free version 

@m1dnight2x  Can you format the external drive?  You'd lose all existing data, so don't do it if you have other files you want to preserve, or else move those files to internal storage first.  Format the drive as NTFS, and if the process fails, formet it to FAT32 and then back to NTFS.

If this doesn't help either, or you can't erase the external drive, do you have enough space to install the game on your internal drive, at least temporarily?  If so, please try that, again in a newly-created folder on the root level of the drive.  There's an unofficial way to move the program files after installation, which isn't completely reliable but may allow you to have the game installed externally while getting around the installation error.

Malwarebytes should be fine, but please disable it while installing Sims 4, just to be thorough.  As long as you don't do anything else at the same time, your computer should be safe.

I found the issue. It's not The Sims or the EA App (I think). The issue is the free My first pet stuff pack. I downloaded the base game without the packs and I managed to open it and then a windows with packs to install popped up so I clicked on restart the game. The My First Pet Stuff Pack automatically started to download and...not download at the same time. It's stuck on "preparing" and the options for stop download or cancel are greyed out I can't click on them. I closed the EA App and restarted the PC then I opened the App again and it automatically started to download the pack again, which is always stuck on "preparing". I checked my settings and all of the auto-update stuff are off.

@m1dnight2x  The EA App will auto-install your packs, or try to, after you've launched the game once.  There's no way around this as far as I can tell, although I do have a suggestion if you want to try it.  Open the game's install location, here by default:

C:\Program Files\EA Games\The Sims 4

With the EA App closed and the EABackgroundService NOT running in the TAsk Manager, create a folder labeled SP14 inside "The Sims 4," then see whether the App will install the pack properly.

If not, delete the folder and create a .txt file called SP14.  Strip the .txt extension off the file name; you may need to tell Windows to show file extensions first.  The App won't be able to try to create a folder in the same location.  This has worked for others who don't want certain packs to install at all, but those packs would have installed properly had the players let them, so I don't know whether it'll help you.  But it's simple enough to try.