Trying to get a client to buy a postman team

We are building an api only application and have begun working with larger clients in proof of concept style engagements. We tried sharing our graphql sdl with them to import to postman. They are currently using the free app. They have been unable to import getting a message ‘no internet connection’ - however, they are able to hit all of our api’s with postman - so we do know they have internet connectivity.

Question: Is postman ability to import an SDL limited in the free app?
If not - what is postman doing differently so they can clear whatever block is preventing them from loading our sdl.

Thanks.

Can you submit a support ticket?