Special offers are made by external companies (Fyber). 
To receive the rewards you need to fulfill all the requirements and conditions specified in the offer.

You can check the status of the special offer you have completed in the "Support" section on the top-right on the Offer Wall. Bear in mind that the rewards can take a few days to be delivered.

Fyber are the ones that can follow up your activity and check the status of your completed special offers. Contact them to check the status of your special offers if you haven't received your reward.

Contact with Fyber: Through the "Support" button on the top-right of the Offer Wall screen
• www.fyber.com (bottom of the page -> Contact Us -> Customer Support)
• customersupport@fyber.com