Tenuere tamen arcem Sabini. Atque inde postero die, cum exercitus Romanus inter Palatinum Capitolinumque collem instructus esset, non prius descenderunt in locum aequum quam Romani - ira et cupiditate arcis reciperandae accensi - montem subiere.
I’m getting a bit confused here…
The Sabines then held the citadel. And then the next day, whilst the Roman army was ordered between the the Palatine and Capitoline hill(s), they did not first descend from there [inde] to the same level as? / whilst? [quam] the Romans - (who were) inflamed with the desire that the citadel should be recovered - passed beneath the mountain [?]
…or they did not descend before (until) the Romans had passed underneath…?
I’m not sure what ‘subeo’ means in this context. Passed beneath? Ascended?