Enable "Install Unknown Apps" in your Android settings for your browser. Download the APK file from the official developer source. Open your File Manager and tap the file to install.
The safest way to get the Delta Air Lines app on Android is through the official app store. Fly Delta on Google Play Store Download DLTA apk
If you are looking for the Roblox script executor, be aware that this is and must be sideloaded. Enable "Install Unknown Apps" in your Android settings
Websites with generic names often bundle malware with the file. Download DLTA apk