Why don't my sub accounts have full access?

My sub account users are saying that they can only make five forms and they are hitting other limits with submissions, file size, etc ... can you please advise?

The sub users must be under the FREE plan only. This was the reason they have limitations that fall within the FREE plan. 

Take note that if you are the main account (paid SILVER plan), it does not include your sub users and will not give them the same plan as yours.

So if the sub users were just creating forms within their account (not within your account), they will be subjected to the limitations of their subscription plan (i.e. if on FREE plan, number of forms is up to 5 forms only)

Please review also the user guide :  https://www.jotform.com/help/232-How-to-Share-Forms-with-a-Sub-account-User

Once you give the sub users full access to your forms, the limitations your forms will use will be within your subscription plan (SILVER plan).