There are native iOS and Android versions available.
The Pulse App is also a webapp and doesn't require an install, but you can still get the easy shortcut added to your homescreen, and it behaves very similarly to an app.
iOS Instructions
1. Navigate to https://app.pulsegrow.com using the Safari browser.
2. Look for the "share" button at the bottom middle of your screen. It looks like a square with an arrow pointing up.
3. Swipe through the bottom grey icons until you find the Add to Home Screen button that looks like a plus inside of a square.
4. Give the app a name, like "Pulse" for example, and then hit the Add button in the top right of your screen. You're done, enjoy your "installed" webapp.
Android Instructions
1. Navigate to https://app.pulsegrow.com using the Chrome browser.
2. Tap the menu icon (three dots) in the top right of your screen.
2.b. In the menu that shows up, tap "Add to Home screen"
3. A popup will appear. Tap the ADD button. You're done, enjoy your "installed" webapp.