Access Denied on IOS

Our institution, which is based in the UK, has recently moved to using federated accounts for Adobe licenced products. Since then we have been working with our userbase ensuring that those that should have access to Acrobat have their IDs setup correctly and can access the software. However, those that are trying to install Acrobat on their iPads are getting an "Access Denied" message when they sign into the Creative Cloud app. We have checked their credentials on the portal and they can use the software on a desktop so we are unable to explain why it won't allow them access on an IOS device.

Can you help please. Thanks.