Sure! Just make sure you have signed up on the first device, and you can login to the same account on other devices.
After installing RedKiwi on your other device, you'll see the screen below. Please touch the 'I already have an account' button. Then, login with the method you used to sign-up for RedKiwi.
If you have further questions about the login process, please contact the RedKiwi customer center. 😄