You must already control a Swamp or Mountain as Dalkovan Encampment enters for it to enter untapped. If it enters at the same time as a Swamp or Mountain when you control no other Swamps or Mountains, it will enter tapped.

Activating Dalkovan Encampment’s last ability creates a delayed triggered ability that will trigger each time you declare at least one creature as an attacker during a declare attackers step this turn. (This usually only happens once per turn, but effects like that of All-Out Assault’s last ability might cause it to happen more than once.) This ability will trigger even if Dalkovan Encampment is no longer on the battlefield. It won’t trigger if you don’t declare any creatures as attackers.