The costs of activated abilities that Robaran Mercenaries gains must be paid as normal.

Activated abilities contain a colon. They're generally written "[Cost]: [Effect]." Some keywords are activated abilities and will have colons in their reminder text.

If Robaran Mercenaries gains an activated ability that's normally linked to a non-activated ability of the creature it came from, the ability Robaran Mercenaries has isn't linked to any ability.

If Robaran Mercenaries gains an activated ability that's normally linked to another activated ability of the creature it came from, those two abilities Robaran Mercenaries gains are linked for as long as that creature remains on the battlefield.