This usually occurs if the phone make/model or OS is not supported. We support the following:
Apple ios target 12.2 upwards, theoretically supported by iphone5s onwards.
Androids target os is pie(9), min supported version is jellybean (4.1).
Should you have the correct device and still have problems, then please report this to the Unibuddy Support Team via Intercom and copy and paste the "Device Info" from the Settings section in the mobile app.