1. Go to integrations. You need to create an integration from your store admin, click on System > Integrations.
2. Create an integration. To create an integration you must first click on the button Add New Integration.
3. Complete the information. In this step you should complete the information, for Callback URL and Identity link URL please copy this URL https://oauth.ecartapi.com/oauth/magento2/access/NrUAVHsfjTJUE0NacgA7mVSogkfTuWTW, see the step 4 before clicking on Save.
4. API settings. Please change Custom to All option in Resource Access field and click on Save
5. Activate. Now you can see the integration created but you need click on Activate to finalize click on Allow.