The first step is to get ready to open the GPS zip file on your mobile device
You are going to need a program for unzipping the file so you can access the individual GPX files. I believe Android devices have something already built in. If your device does not seem to have something like that, you will need to download one from the Play store. Obviously I can’t give detailed instructions how to use an app when I don’t know which one you’ll end up with.

For IOS, you will need an unzip app from the app store
I recommend one called “Unzip Tool” by a developer called “tao xu”. There is a free version (it displays advertisements occasionally).

Then you will need the Gaia GPS app
Log into the App store and do a search for “Gaia GPS”. Once you have it installed, open it, skip the account signup, and step through the quick start tour. Give Gaia access to your device’s location services when prompted. Then go back to your home screen.

The next step is to get the GPS zip file onto your device somehow
I can’t provide detailed instructions for every model or platform. But a common way might be to e-mail the file to yourself from a PC. Or, I can e-mail it to you if you don’t have access to a PC.

Here are some steps for getting the file unzipped and into Gaia from e-mail on your device:

With Apple IOS:
Open the e-mail with the attached file.
Tap on the file attachment.
Tap the “upload” icon in the upper right corner (looks like a rectangle with an up arrow in it).
Swipe the first row of colored icons and tap the Copy to Zip Tool icon.
Zip tool will ask you if you want to unzip the file. Tap OK.
Zip tool will create a folder with the same name as the file. Tap it.
You should now be seeing a list of individual riding area GPX files.

Import The Files
Note: Be VERY careful with this, a single import brings in just a few tracks, but also brings in dozens of waypoints.
If you import the same file twice you will have duplicates, and deleting hundreds of duplicate waypoints is not easy.
Note: If you sign up for a Gaia supscription you can manage your data using a web page which is easier.

Tap the Upload icon to the right of the first file, and tap “Open in …”.
Swipe the first row to colored icons and tap “Copy to Gaia GPS”.
Gaia will open, and after a moment, will say “All imports complete”. That riding area has now been imported.
Double-tap your Home button, swipe back over to the Zip tool screen, and repeat for the next GPX file.
Repeat this process with every file.
Note: The “All.gpx” file is too big, and Gaia will not import it.
Note: You can import “Republic_All” and skip Republic_North and Republic_South. Same with Conconully.

The Zip Tool program will periodically interrupt you with advertisements. Just close then when they come up and continue.

Once you are done, zoom out the map in Gaia and you will see the track lines and waypoints on the map.
You can now delete the folder full of GPX files and the zip file from the Zip Tool app, or just delete the Zip Tool app from your device which will also delete the data.