How do you access the signature shot mission on watch dogs

The following packs Breakthrough, Exclusive Missions, Palace and Signature Shot the bonus/boost/weapons/perks will not be available until you have completed the mission "A Wrench in the Works ", while the outfits will be available once the content has been activated.

The content from the Blume Agent, Untouchables, DEDSEC Shadow, Club Justice and Cyberpunk will be available upon activation of the code.

Source: https://support.ubi.com/en-gb/FAQ.aspx?platformid=35&brandid=1979&productid=2841&faqid=kA030000000efAECAY