Over 25 user Web Clients are required
Web Client licenses are only available for 1 , 2, 5, 10, 15, 20, or 25 users
Each Web Client session can support up to 25 concurrent browser sessions, for a large system that requires additional sessions additional Web Client servers can be used, each supporting up to 25 Users.
Each Web Client server however will have a different IP address / URL, so if a user finds one server fully utilized, they will then need to connect to a different server/ address to connect to the system.
Also see How to determine if SU, LAN, or WEBC security keys are required for your project for information on Licensing.