The instruction in this document will describe how to enable bigger http request and responses

You will get an error similar to this in the log file.

HTTP GET failed (reason: Response entity too large (max: 2097152 bytes, actual: 3000000 bytes))

Open the configuration UI.
Choose Advanced.
Select the pen next to modules.
Find the "com.phenixidentity~phenix-httpclient-mod" section

Replace following parameters with bigger values

"request_body_max_size": "2097152",
"response_body_max_size": "2097152"

This solution is for http sizes.
For file sizes look at this instruction for Global parameters and change the httpRequestBodyMaxSize parameter.