Ordinarily a software release is one file. For the echomaps the name is usually something like echoMAPwithSDCard.exe.
This is downloaded to the computer. Double clicking on that file will run it.
When it runs it will create a software update SD card.
That update card will have one folder named Garmin. Inside that folder will be another folder named updates and a file named GUPDATE.GCD
Inside the updates folder will be numerous files with names like 0.dat, 1.dat, 2.dat....... and possibly some with other type names.
If the card you have created was not created by the Garmin .exe file you need to be 100% certain that you have all the files in all the right places. If you have enough of them for the unit to think it has a valid update card and some of the files are missing there is a really good chance you will brick your unit. The card you have been using is not set up properly. You are lucky that the update process did not start.