Open the app project you would like to download. Choose Apps | Download selected app project (.aia) to my computer to export the source code (blocks) for your app. The source code is downloaded as an .aia file.
If you send it to a friend, they can open it with Apps | Upload app project (.aia) from my computer.
Package the app (.apk file) by going to the "Export" menu on the Thunkable toolbar.
Select "App (save .apk to my computer)." A pop-up box (seen below) should alert you that your download has begun. Note: The other option (provide QR code for .apk) produces a scannable QR code that will download the app for two hours. You can share this code with others, but they have to use it within 2 hours of your generating it.
You can also download the apk directly from your apps home page by clicking on the download arrow next to any app project.
Once the build completes, you can email the app (".apk" file) to your friends who can install it by opening the email from their phone. If you want to distribute it more widely, you can upload it to a website that both you and your friend can access. You can also distribute your app on the Google Play Store.
Anyone installing your app (which is an ".apk" file) directly, instead of from the Play Store, will need to change the setting on their phone to allow installation of non-market applications.
To find this setting on versions of Android prior to 4.0, go to "Settings > Applications" and then check the box next to "Unknown Sources". For devices running Android 4.0 or above, go to "Settings > Security" or "Settings > Security & Screen Lock" and then check the box next to "Unknown Sources" and confirm your choice.