If you have not yet install the app and configured your chargers, see this help center article for more information: Connecting FreePower chargers to the mobile app
Tap the main settings icon and then tap "Clear Discovery" to clear the list of chargers. This will force the app to immediately start looking for chargers again.
Restarting your phone can sometimes clear networking errors that are prohibiting your phone from connecting to FreePower chargers.
Performing a hard reset will bring your charger back to factory settings and allow for you to re-attempt to pair your charger to your Wi-Fi network.
See this article for instructions on how to perform the hard reset: Hard-Reset
After performing the hard reset, connect your charger to your Wi-Fi network through the app: Connecting FreePower chargers to the mobile app