Device model should be entered exactly as it is. It can be found in two ways:
After application association with device:
Install application as it is mentioned in manual
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In “System” section is option “Model” and value. If it is empty, wait for couple of minutes for synchronization to finish.
In mobile device:
Depending on the device can vary, but usually it can be found in the following order “Settings” -> “About device”
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