You can get the authcode for your domain in your easyname Control Panel.
Please log into your account and click on the menu item [Domains] . You can now see a list of all your Domains.
On the right side next to your Domain, click [Manage] (pen icon).
Scroll down to the bottom and click on the [Show Authcode] button. In the final step, you can just copy the authcode and hand it over to your new Provider.
Tip: You also have the option to remove the transfer lock from there. You have to make sure that the status "possible" appears in the transfer information column.