If using the AutoDJ this means some files have been uploaded as VBR (Variable Bit Rate) setting. To resolve this, all files should be CBR (Constant Bit Rate), ideally all files should be encoded the same settings.
If it is a Live Broadcast, this means the encoder is set as VBR and not CBR. Simply setting encoder to CBR will resolve this.
The error essentially means you are feeding VBR files into the system, VBR files may be encoded - as the name suggests - with varying bit rates, this can sometimes be above the account allowance, hence the error.
This error can also be searched online by you to confirm the above and to know more. There is nothing server related to do.