The steps you will take will vary depending on the source of the GEDCOM. For this walk through, I'm going to use Geni.com as the source.
The process is straight-forward, but at the risk of being overly detailed, the sequence goes like this ...
Once you export your tree from Geni.com, the GEDCOM file will be sent to the email address you used for registration. I am assuming that your phone or tablet will receive this email. Clicking on the Download link in this email will open the Geni.com download page.
Clicking on the "Download my GEDCOM file" button will start the download. You will see a notification icon in the upper left hand corner of the screen indicating that a download is in progress.
Swiping down on the notification bar at the top of the screen will list all of the notifications, the one at the bottom tells me export-geni.zip has now been downloaded to my device. It is a zip file which contains the GEDCOM.
Tap or click on export-geni.zip in the notification view above and ASTRO File Manager will open the zip file and show its contents: export-BloodTree[.ged]
Do a "long press" on export-BloodTree to bring up the context menu and select the Copy command to prepare for the Paste we will do next.
Now click the "Up" button to move out of "zip file directory" and into /mnt/sdcard/download
... and then Paste
Launch ezGED and enjoy ...