Action Details
Requirements and how-to articles for Snapchat's action:

paid action
Story Ads contain 3-20 Snap Ads and appear on the Discover screen alongside other Stories.

You need this to get it done:

Business Account
A Snapchat Business Account is required in order to use the Snap Ads Manager.
The name for your Story Ad which will show up in your creative library, reports and notifications.
The headline which will appear in the upper left corner of your Story Ad (maximum of 34 characters including spaces.)
Brand Name
The brand name which will appear in the upper left corner of your Story Ad (maximum of 25 characters including spaces.)
Tile Headline
The headline which will appear in the bottom left corner of your Story Ad's Discover tile (maximum of 55 characters including spaces.)
Tile Background
The background image for your Story Ad's Discover tile.
File format: .png
Maximum file size: 2MB
Resolution: 360 x 600 pixels
Maximum bit depth: 8-bit
Leave a 175 pixel buffer zone at the top of the image to ensure your logo does not conflict with any important image elements on the vertical Tile.
Tile Logo
The logo which will be shown on your Story Ad's Discover tile.
File format: .png (with transparent background)
Resolution: 993 x 284 pixels
Image Snap Ad
File format: .jpg/.png
Resolution: 1080 x 1920 pixels
Minimum aspect ratio: 9:16
Maximum file size: 5MB
Video Snap Ad
File format: .mp4/.mov
Video length: 3 - 10 seconds
Resolution: 1080 x 1920 pixels
Maximum file size: 32MB
Encoding: h.264
The following attachment types are available for users to engage with on your Story Ad:
App Install
Deep Link
Longform Video
Target Audience
Choose your target audience based on location, age, gender and interests.
Set how long you would like your ad to run for (you can either set start and end times or have it run indefinitely until you decide to pause it.)
Budget and Payment Method
Set either a daily or total budget for your Story Ad campaign, and set a payment method (credit card or PayPal.) You can also set a goal (impressions, story opens or installs) and bid type (auto bid or max bid.)
Business Address
The address associated with your business (street address, city, state/province and zip/postal code.)
Requirements missing or found errors? Report

How-To Articles
A list of useful links for you:

Snapchat Business Center - Story Ad Specifications
Official Story Ad specs, restrictions and creative recommendations.
Link missing here or found errors? Improve How-Tos