cannot access mobile app

cannot access mobile app

I've created an account and downloaded the IOS mobile app at once. When I login the mobile app, it says "invalid username or password", but everything is going well on desktop.

BTW, my Apple App Store's country is China, but I created the account with @zoho.com. I know Zoho China is @zoho.com.cn

Is this an issue that I cannot access mobile app or there's any other problem?

Thanks!