Whenever Talus Paladin or another Ally enters the battlefield under your control, you may have Allies you control gain lifelink until end of turn, and you may put a +1/+1 counter on Talus Paladin.
The choices you make as Talus Paladin’s ability resolves are made individually. First you decide whether to have Allies you control gain lifelink until end of turn. Then, regardless of that decision, you decide whether to put a +1/+1 counter on Talus Paladin.