This article details the Contractual and License related constraints on the number of External Users or Contributors who can be invited inside Communities and Groups in a Jive Cloud/AWS instance.
For a Jive Cloud/AWS instance:
The External Contributors are included in the purchase of Jive Cloud licenses. No additional purchases required.
The 50:1 Ratio Contstrant is in place wherein:
50 External Users are allowed for every paid Internal User.
No more than 100 External Contributors allowed per Group (Contractually).
Note: It is not a technical restriction.