Admin SDK Auth Errors

[moogmusic]

I'm trying to set up the GSuiteForSplunk Input Add-On on Google Cloud - I've followed the instructions (I think) and created an OAuth2 token and set that up in the app but I'm getting 100% errors accessing the Admin SDK API. I think the problem could be the account I'm using to authorise the token (I'm using my normal Google account but it feels like I should be using the Service Account?) but in the main, I've no idea what's wrong.

Please help

Thanks

[moogmusic]

It also looks like splunkcloud.com needs to be an Authorized Domain for my org for the app to be able to access the APIs?