I would like to know what access token I require to achieve the following.
My Meteor app crawls various RSS feeds and makes a daily digest. I would like to automatically tweet about the daily digest when it is created, using the app's Twitter account.
As I see, in the doc, it seems that I need to use application owner access token and create my app using the app's Twitter account. Is this a correct approach?
Yes, that's correct. It's quite simple too.
Then depending on the software/language you use there's a plenty of existing packages that can help you access and obtain the information from the API.