There is no need to create own Tumblr APP, you can use our default Tumblr APP from Social Login product on your online store.
If you want to use your own Tumblr APP with your store name & logo then please follow this video guide.
Go to this page http://www.tumblr.com/developers, Sign up on Tumblr and then click on API link:
That's all! Just copy & paste Tumblr Consumer Key and Consumer Secret into the fields and click `Save Changes` button - https://growave.io/admin/service/services
If you face any problems then feel free to contact us - Contact Us