Are there any limitations regarding the processed data volume?
No, there is no special limitation for this.
Basically the Plugin can process any amount of records.
The only limitation are the known API limits of the salesforce environments you are using and the maximum memory size allocated to the nodejs processes.
If you are facing out-of-memory issues, try to optimize queries in the export.json file.
Also refer to the related salesforce documentation: API Request Limits and Allocations