Adding new users
In order to add a new user to your account, you just need to click in Settings > Menage Subscription:.
Then, click in Manage users > Add new user.
After that, you only have to add the email of the accountant, and choose the level of access, between Administrator and Contributor.
With both fields filled, just click in Save.
The credentials for your accountant to access will be sent to the email that was added.