Hi Ayecona,
You are currently using the Adobe Sign free account which does not have the Integration feature.
For integration testing, you may register for the free developer edition of Adobe Sign from here Create Developer Account, APIs for custom applications | Adobe Sign
Please make sure that you use an email address which is not registered under any other Adobe Sign account.
The settings are not enabled by default to access the Integration Key in the free Developer account.
I would recommend you contact Pre-Sales team to get the settings enabled. They will be able to provide pre-sales technical assistance to you.
Please refer to this link https://acrobat.adobe.com/us/en/sign/pricing/plans.html to get in contact with them.
Let us know if you need any help.
Regards,
Meenakshi