There could be several possible reasons for this. Keep in mind that the Walabot DIY Plus works with most phones operating Android 7.0 or above and must have USB OTG (On-the-Go) support. However, the Walabot DIY Plus is not compatible with iPhones or iOS-based computers and tablets.
On some phones, it is necessary to manually enable the USB OTG feature. For most phones, this can be done by going into Settings, then Advanced Settings, and then OTG Storage. Alternatively, you can find OTG through the Settings search bar.
Note that once OTG is enabled, it may turn off automatically after 10 minutes of inactivity or if you leave the Walabot app.
If your phone's OTG is enabled and it is still not connecting to the Walabot, make sure your phone is running the latest software version. You can check for app updates by visiting the Google Play store and going to the Walabot DIY app page. You can also update the app by uninstalling and reinstalling it.