Can I invite or add external/guest users to my Viva Engage community?

Question

I am trying to set up Viva Engage Communities for group of interns/students. Originally I wanted to have them join with their own personal accounts (With Teams I have successfully registered them as guest users in Microsoft Admin, and invited them).

With Viva Engage though, I am struggling to do the same. Research shows I should be able to enter a guest's email address in the Add Member Panel of the Community. But when I type in the email, it doesn't give me the option to add them. I'm trying the steps found here:- https://learn.microsoft.com/en-us/viva/engage/work-with-external-users/add-external-participants

Other info tells me to try and set up an external network, but even though I am a Global Admin and owner of our Microsoft Business account, I also don't see this option.

Can anybody point me in the right direction, or have these features been removed?

BTW, we are working from Microsoft Business Basic Accounts