Error Code: 0x80073CF9 Downloading Forza Horizon 3 and Other Apps Not Working.

To startwith, you should run basic troubleshooting for Store Apps and check after each step (I would recommend you test with some other app as definitely testing with 60gn of Forza will not be tenable) -

1. Run Windows App Troubleshooter
Windows Key+X > Click Settings > Click Update & security > Click Troubleshoot > Scroll down to the bottom > Click Windows Store Apps > Click Run the Troubleshooter

2. Reset Windows Store through Command Prompt
Type cmd in Windows Search box > Right click on Command Prompt > Run As Administrator > Type WSreset.exe and click Enter > Reboot your computer

3. Re-register All Store apps
Right click on Windows Start > Right click on Windows Powershell (Admin) > Copy the following from below and right click in Powrshell to paste ? Enter > Restart your computer
Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

4. Uninstall & Reinstall Store
Right click on Windows Start > Right click on Windows Powershell (Admin) > Copy the following from below and right click in Powershell to paste > Enter

Get-AppxPackage -allusers *WindowsStore* | Remove-AppxPackage

Copy the following from below and right click in Powershell to paste > Enter > Reboot your computer

Get-AppxPackage -allusers *WindowsStore* | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register “$($_.InstallLocation)\AppXManifest.xml”}

5. Run Built-in & Guided Walk through Windows Update troubleshooter
Built-in : Type troubleshoot in Windows Start Search box > Click Troubleshoot > Click Windows update > Troubleshoot
Guided Walk though - https://support.microsoft.com/en-us/help/10164/...

Let me know if you have any more question or require further help. If above didn't work, I will supply more troubleshooting steps to solve this problem.

1. Troubleshooter didn't identify the problem

2. Tried doing WSreset many times and never works

3. 

Add-AppxPackage : Deployment failed with HRESULT: 0x80073D06, The package could not be installed because a higher
version of this package is already installed.
Windows cannot install package Microsoft.VCLibs.140.00_14.0.24605.0_x64__8wekyb3d8bbwe because it has version
14.0.24605.0. A higher version 14.0.25426.0 of this package is already installed.
NOTE: For additional information, look for [ActivityId] aefea623-cf10-0000-7f65-ffae10cfd301 in the Event Log or use
the command line Get-AppxLog -ActivityID aefea623-cf10-0000-7f65-ffae10cfd301
At line:1 char:38
+ ...  | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.I ...
+                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (C:\Program File...ppXManifest.xml:String) [Add-AppxPackage], Exception
    + FullyQualifiedErrorId : DeploymentError,Microsoft.Windows.Appx.PackageManager.Commands.AddAppxPackageCommand



Kept getting red lines like that ^^

4. Reinstalling didn't work

Things I've noticed: 
I can download small things (candycrush, bow masters, roblox), but not big downloads like FH3.
FH3 still has the same error and still does 294 MB of 294 MB!

5. Did the troubleshoot on the first part, now my store can't open.

Two ways I have seen other gotten this game to install and work, do it from another user account.

Open Start
Type: cmd
Right click CMD
Click Run as administrator

At the command prompt, type:
net user administrator/active:yes

Hit Enter

Close command prompt, restart, then try signing into the Administrator account.

Try downloading the game again.

Option 2:

Reinstall Windows 10, then try installing again:

http://answers.microsoft.com/en-us/windows/wiki...

New problem:

Code: 0x80070005

And this is happening in the Administrator account?

Nvm

I did it in the admin account

Here is the actual new error code:

0x80070520

What is the exact make and model?

Open Start, type: system information
Hit Enter
Click System summary
Look in the right pane

Copy the system sku info into reply here.

See example: https://imgur.com/qzektpA

Perform a repair upgrade, after completion, check Windows Update, install the latest updates then try again.

http://answers.microsoft.com/en-us/insider/wiki...

H110M-A

Everything can download, but FH3.

If I go on my other account I get the error: 0x80070520

If I go on admin I get: 0x80070005

Thanks Aldan, but could give me some additional details like video card installed, amount of hard disk space, memory and also the version of Windows 10 installed?

OS: Microsoft Win 10 Home 

Version: 10.0.16299 Build 16299

Video Card: GTX 1080

CPU: i5-6500

HDD Space: 922 gb total, 854 gb left

Memory: 8gb

Update:

Went on admin and still the same error: 0x80073CF9

Going to bed in 15 min, I will reply to you soon.