This article explains how to increase the number of static resources (static files) that you are allowed to upload in a place, being a Space, a Sub-space, or a Group.
The system property that governs this parameter is jive.statics.global.maxCount, that defaults to 300.
This property can be increased, but it is advised that you first consider if it is really needed, or it is better to split (or branch out) to a different space or sub-space. The reason is that, if the space is so large, it is better to divide the content in order to organize it better.
Having taken this into consideration, if you still need to increase this parameter: