Rainbow Office use sandbox

Hi!
I have created my application and should now test it through the sandbox account.
I have to use Rainbow Office and not RingCentral.
From RingCentral I see that to activate the account just use CTRL + F2 (https://community.ringcentral.com/questions/9845/ringcentral-phone-with-sandbox-account.html) but from Rainbow Office it doesn't work.
How can I do?

Regards