Having downloaded your files, you are best off using the software provided to transfer them to your bike computer
However, if you have a Garmin and use a Windows computer (this may work for Apple, but we don’t have one on which to test), we do know a short cut:
Connect your Garmin to your computer
After a short while windows should recognise it and show this in explorer (the drive letter may differ):
Open the Garmin drive, and navigate to this folder, G:\Garmin\NewFiles (replacing G: as appropriate)
Copy or move (I recommend copy) the GPX or FIT files you have downloaded to this folder. This may take some time (the Garmin can be slow receiving data). In our experiments a Garmin Edge 820 happily took the GPX or FIT files, whereas an older Garmin Edge 500 only took FIT files. The author prefers GPX files as they are more readable.
Disconnect your Garmin device and then restart it. At this point it will process the new files and may take some time to complete that process it will flash “Working…” at you whilst doing this. On newer devices this may take very little time.
When complete, if you go through your menu structure to courses and you should see the list of downloaded daily rides