Login failed through business chat sandbox

For testing business chat, i need login business chat sanbox, but always faild and give me message like below:

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Device is not supported

Business Chat requires the following OS version:

iOS - 11.3 and higher

macOS - 10.13.4 and higher

watchOS - 4.3 and higher

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but mine testing env highest version is:

iOS - 11.2.6

macOS - 10.13.3


please help.


BTW:

iCloud, iMessage, Business Chat Sandbox use one account like apple required.

Login failed through business chat sandbox
 
 
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