The Sidewinder Elite Skin and Outbreak Packs were held back by distribution bugs, and should arrive March 7th 2018 or “soon” thereafter.
Both of the Elite skin and Packs seem to be experiencing an issue where players simply aren't receiving them. Ubisoft investigated and is resolving both cases and has an official Reddit thread for keeping watch on their status. Keep an eye on that thread.
Four Outbreak packs: Fix being deployed, they should arrive today.
As originally reported on Ubisoft's twitter (6th March):
We are aware that some players did not receive their 4 free Outbreak Packs during the outage. We are investigating, and will update you when we have more info.
For a list of known issues, please refer to the thread here: http://www.reddit.com/82fnn1/
Ash's Sidewinder Elite Skin: Fix being deployed, should arrive “soon”.
Ubisoft confirmed on Twitter (6th March) they've removed the skin temporarily and are working on a bug with distributing it:
The Ash Sidewinder Elite is being removed from the shop while we actively work on the fix to get it to all players that qualified to receive it for free.
Ash's Black Viper Elite, from the Outbreak Collection, is still available through Outbreak Packs.
The Reddit thread says they've found a fix for the issue and are working on getting it out.