If you are looking for relevant solutions for Garmin Express Download Failed on Windows, here is the solution. But before that, I would like to state why these happen. 

You need to fulfill the requirements before using Garmin Express. Missing out a single requirement can lead to this problem. The requirements are:

1024 x 768 screen resolution
Windows 7 SP1 with Microsoft 
.NET 4.5.2 version
1 GB RAM
A USB port

If the operating system has automatically blocked its ".exe file" while downloading Garmin Express, you will come across this issue. 

If your computer does not have much space to install Garmin Express, you will receive this message "Garmin express won’t install on Windows".

Whether you are using Windows OS, .NET framework, or Garmin Express Software, if you do not update the software regularly, you will face these issues. 

If you start intervening Garmin Express, or Windows you will receive the message saying Garmin Express Download Failed on Windows. 

If there is a shortage of space in your device, you need to face this problem. That is why; you must ensure that you have enough space available in your device.

Now that you know what the reasons behind this error are, you can simply eliminate the cause. By eliminating the cause, you can ensure that you will not come up with this issue. In case the issue comes up, the process to rectify it is stated below. 

The process below will explain to you how to eliminate the error. 

1.  Try to install the software from a different system and check whether you are facing the same error or not. 

2.  In case you are getting the same message change the source. 

3.  If it gets installed, then you had a problem with the system and not with the Garmin device. 

4.  To make your system work faster, reboot the system. By doing this, you will create some space in RAM. After that, try to install Garmin Express. If the process gets to freeze, click on CTRL+ALT+DELETE together. 

5.  Select on the "Processes" tab and look for the process named "msiexec.exe". 
Right-click on the "End-Task" button and select on "OK". After that, you will return to the normal window page. 

6.  After that open "C: Drive" on the system. Check if there are any Garmin Express folders available or not. 

7.  If it's there, you need to uninstall it from the "Control Panel Window". 

8.  And then you need to run the Garmin Express installer as administrator. 

9.  After that, you can see that the problem has been solved. 

Well, the process is quite simple and also explained systematically. Do not skip a single step as you will not be able to eliminate the error if you do so. In case you are not able to solve the error, you can get in touch with the experts.