The manager has told you all very diplomatically that you're not wanted in the foyer.
They can make more money from other customers, I'm afraid, and maintain a more peaceful, perhaps cleaner, less cluttered atmosphere in their lobby.
This is very important sales area for a nice hotel which relies on business bookings and conference trade. People attending conferences and staying in the hotel use the lobby as a meeting area - it is not 'done' to conduct business meetings in each others' rooms! They will not book conferences if they're going to be subjected to a playgroup environment during business chats.
You must have been seriously impacting their trade (whether you intended to or not) for them to move you along in this way.
It's like restaurants round here who won't serve hen or stag parties - the noise, hassle and damage drives away their regular customers, and they just can't afford for that to happen.
Why not ask them if you can meet up on a Saturday, if you really like the place? Business trade is practically non-existent, then.
If they make another excuse, you'll know the fault lies with your group, and you could ask for some feedback about what you could do to be more acceptable. But in reality, maybe just wise up and accept it's the wrong place for you all. Hopefully can make arrangements to meet up somewhere nice which is a more suitable environment for you all, where they'll welcome your custom.