This modpack is hidden and will not show up in the modpack index.
If after attempting to update you get "Failed to download from (insert link here)" I dont know how to help you. In the cases it happened to me the link it gave was different from the link displayed on the website. I saved it and everything. So my suggestion is to simply try again later. (It only applies pretty much right when the pack updates. so like I said if this happens wait about 2 mins.)