You will need an account already in Synnch to logging with Xero with a matching Email address to your Xero email address.
On the Synnch login screen click login with Xero
You will be redirected to Xero and ask to login to your Xero account.
If you have more then one Xero file attached to your account you will be asked to select a business you will be attached to.
Note: this will not connect the file to your Synnch account at this stage.
Agree to the permissions required to use Synnch with Xero.
You will be redirected to your dashboard.
If you have an account in Synnch it will connect automatically. You will be logged into your account
If you do not have account in Synnch you will redirect back to the login screen and will have to Sign up to Synnch you can do this this with the sign up to Synnch button.
Next time you click the sign with Xero account you will be automatically logged in Synnch.