Hi Denis,
You may refer below for my responses to your inquiry :
1. A test account level developerToken generated from your production MCC account should be enough to make API calls using the new Google Ads API. There should be no need to request for basic access approval.
2. Yes, you need to create your test account hierarchy separately and you need first to create a new test MCC account. You can fill up and submit this
form to do so. Once done, you may then create OAuth credentials specific to your test accounts. Afterwards, using your test MCC as the clientcustomerId and the credentials you generated for it, you may then proceed in
creating your test client accounts and the other testing scenarios that you have planned.
I hope this helps and feel free to write back if you have any further clarifications.
Thanks and regards,
Peter
Google Ads API Team

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