Can it be used by multiple people? Also, at that time, is it possible to set user rights that allow only some promotions to be viewed and operated?

Yes, it can be used by multiple people within the team. It is also possible to set user rights by narrowing down the usage target to some promotions.

You can invite other users by clicking the icon at the top right of the Shirofune management screen → Team settings → Add new member management button.

At that time, by setting the role of the user to "operation staff", selecting the target promotion, and then inviting the user, it is possible to add users by narrowing down the usage target.

Please refer to the following article for details on user rights.

https://shirofune.zendesk.com/knowledge/articles/360003798292/ja?brand_id=114094056092