The nice thing about Armada is that the keywords used are clearly defined. Take a look at the Rules Reference Guide, pg 10, the section on 'Shields'.
Each ship begins the game with its shield dials set to the maximum shield values shown in the corresponding hull zones.
The 'learn to play' guide, on page 5, has a infographic in the lower right corner also specifically pointing out the value indicated as the 'maximum shield value'.
(The thing to be careful of is that the wording is, indeed, extremely precise. If you find words that seem like they might be synonyms of each other...for game purposes, they are completely unrelated. 'Maximum' means one thing and 'highest' means another, potentially totally different, thing.)