Stakeholders arent “required” to attend and / or participate in standups but they certainly can attend standups if they want to. As a general rule, those stakeholders shouldn’t actively participate in this ceremony and they should just observe the conversations that happen. Scrum Master should communicate this message to them prior to the standup. Once all the team members have shared their plans for the day (what did you accomplish yesterday, what are your plans for today, any impediments) the stakeholders can ask questions if they have any.
As a matter of fact, even Scrum Masters aren’t “required” to attend the standups but if the teams are new then obviously SM has to facilitate the standups.