While exporting data through Data Management there is a size limit that currently set to 256MB. Following link refers to it: https://fix.lcs.dynamics.com/Issue/NotFixed/?bugId=3824019&qc=103b9b18eb6754aaa53dd906fa35037b9a803b5c398a816910becb3f1ae9aa81

However, with the increasing data volume over the time in your ERP this limit becomes a bottleneck for export. We have faced the similar issue recently with one of our customer and the situation becomes annoying.

I would suggest to please increase this limit to at least 500MB or preferably to 1GB.

Thanks,
-Moin