@Anonymous Thanks for your reply. From your description, I know that when using the same conditional access policy, this error message occurs in iPhone and Android, not iPad. If there is anything misunderstanding, feel free to let us know.
Could you please get the screen shots of the conditional access policy? We will do the test in our lab.
At the same time, I find that the following article shows how to configure conditional access policy. We can read it as a reference.
https://techcommunity.microsoft.com/t5/microsoft-endpoint-manager-blog/microsoft-edge-on-ios-and-android-now-supports-conditional/ba-p/476091
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