See below the error and how to resolve it.
When you have both the Education and Case Management side of Synergy, the setting for Case Management is inherited from Education.
Please navigate to the following:
Education Client.
System Manager.
Options.
Common.
File Store.
Change the value in the field for Maximum Allowed File Size (Megabytes) to the desired amount, then save.
This should then allow you to upload documents larger than 5MB in Case Management.