Although not common we have seen users who are able to login into their web account but are unable to login into their android app.
Almost always this is because internet access has been blocked to ClockIt via the OS settings. Some manufacturers like MI, ASUS, REDMI, VIVO have custom apps that enable access to the data via wifi or SIM. These apps also have options to enable which SIM should provide the data in case of a dual SIM phone. In such cases you will be able to use the internet on the phone on Chrome just fine but ClockIt might still fail to login.
Since there are hundreds of brands we will not be able to provide details instruction for each manufacturer, but here are the instructions to troubleshoot with the stock OS.
Download Speedtest by OOKLA to test your internet connection to make sure you have data enabled on your mobile. If your internet test fails, chances are that your internet has been blocked to this app too.
Go to Settings > Apps > ClockIt on your android phone.
Now click on data usage and ensure that the following.
Background data. [ENABLED]
Unrestricted data usage when data saver is on. [ENABLED]
Disable all cellular data access [DISABLED]
Disable all wifi data access [DISABLED]
Next click on permissions and ensure that the following.
On most other android devices from other manufacturers, you will find the manufacturer apps to manage these exact settings.