Once you have decided which Ark server(s) you’d like to join at https://www.chaosgaming.net/ark/, click on the Mod Collection link. At the top of the list of mods, click on the “+ Subscribe to all” button. Then wait 🙂 For me this has downloaded them all quicker than individual subscriptions.
Sometimes, after playing for a while, Ark has a fit and gets confused, giving mod mismatch errors and such. First restart your Steam client. If it does not take care of the problem one answer is to reinstall the mods.
Go back to the above page and click the “X Unsubscribe to all” button. Then head on into your files on your computer: