Hello Yuki,
I was able to reproduce your errors using Unity 2019.4.34. As @BBIT-Solutions suggested, you are seeing these errors because this version of Unity is no longer officially supported by ARDK.
To resolve your issue, please use at least Unity 2020.3 when using ARDK. I tested with Unity 2020.32, 2021.32, and 2022.1 with no errors. You will also be able to right-click and see the ARDK tab to add your ArdkAuthConfig once you update to a newer Unity version.
Please be sure to check our Announcements page to keep up to date on ARDK releases and Unity compatibility. Thank you!