These steps refer to the JSON key creation as required as a part of the Google Developer account setup. The original JSON key creation steps can be found here.
During the course of this process, you may see the following error:
This is due to the Google account that you used to create the Google Developer account being a GSuite/Google Workspace account, and it does not have the permissions to create service account keys.
This permission is turned off by default for many GSuite accounts for security purposes, but below are steps you can use to turn this permission on.
However, in order to do this, you will need to at least have the Organizational Policy Administrator role in your Google Workspace. Even if you are the Super Admin, you may not have the rights to edit organizational policy. You can check if you are an admin and which role you have by logging in to this page: admin.google.com
If you cannot access the above page, then you are not an admin of any kind in your organization and will not be able to resolve this issue without the Super Admin or another admin in your organization expanding your access.
Login to the Google Cloud page in an incognito/private browser session: https://console.cloud.google.com
From here, please refer to the above picture to make it clearer, but you'll want to click the three horizontal lines at the top left to see the menu, and hover of the > next to IAM & Admin. This should expand the list of options, where you'll see IAM as well as Organization Policies; these are the two pages we'll use. First click on IAM
Find your user in the list on this page, and click the pencil to Edit principal as shown above
Give your user all of these roles, then click Save
After this, navigate to IAM & Admin > Organization Policies. This should get you to the above page, where you'll see a long list of permissions. There's a little search bar on this page, and you can start typing in "service account" and click Disable service account key creation once it shows up
Once this permission is alone on the list after you click it, click on the three vertical dots on the right -- if you're logged in as an organizational admin, you should be able to Edit the policy
From here, we're on to the above page, where you can change the policy to Customize and then Edit rule and change Enforcement to Off
You'll want to make sure you click any Done or Save buttons, but after that I would try the JSON steps again and you should be good to go!