Hi there, Tim. 

Thanks for dropping by here in the Community. Let's work together and fix the error you're seeing.

As mentioned by my colleague MichelleT above, we first have to ensure your computer meets or exceeds the system requirements for QuickBooks Desktop. You can see the detailed information in this article:

QuickBooks Desktop system requirements

Since you have over 300GB available space on your drive, let's try to set up folder and access permissions. Then, clear the memory by deleting files from the %temp% folder. These processes help empty the storag and fix some installation errors. 

To set up folder and access permissions:

• Windows 10, 8, and 7

1. On your keyboard, open the File Explorer by pressing the Windows logo + E keys.
2. Go to C:\Users\[Username]\AppData\Local\Temp or type %temp% in the address bar.
3. Right-click the Temp folder, then select Properties.
4. Choose Sharing and click Share.
5. Add the Windows User Profile and the corresponding QBDataServiceUserXX for your QuickBooks.
6. Set the permission level of both users to Full Control, then click Share.

• Windows 8.1

1. Choose the folder and select Share.
2. Go to Advanced Security, click Add and choose Select a principal.
3. Pick Advanced, then Find Now.
4. Choose the user and select OK
5. Click Full Control and OK.

To delete files from the %temp% folder:

1. On your keyboard, open the Run window by pressing the Windows logo + R keys.
2. Type %temp%, then select OK.
3. Press Ctrl+A, then Delete. 
4. Retry extracting the installer package. The file name depends on the edition and version of your QuickBooks (for QuickBooks Desktop Pro 2018 = QuickBooksPro2018.exe).
5. Double-click the downloaded file, then follow the prompts.
6. If you have an existing file extractor installed on your computer, use it to unpack the installer.

For more details, check out this article:

There is not enough space or Your system only has xxxMB of memory when installing QuickBooks Desktop

These steps should generally help rectify the error you're encountering.

Be sure to update me here on the results of your testing, I want to ensure this matter gets resolved.