Depends entirely on the source/master codec.
Ninety minutes of “2K” at 23.98fps will occupy approximately:
1.5 Terabytes in Uncompressed 10-bit and will require a transfer rate in the neighbourhood of about 250-270 Mbits/sec. Similar if you export a dpx sequence, although the individual image files in the media folder will be about 10 or 11 MB per frame. Again, all these numbers depend on bit depth (8-, 10-, 12-, 16-) and actual resolution — “2K” can mean anything from 1998×1080 to 2048×1556.
OR-
About 100 GigaBytes or so in any of the lossless 422 intra codecs like ProRes or DnxHD and about 10% of the transfer rate.
If you export with handles or do not trim the source clips, you will, of course, be exporting much more than 90 minutes worth of material.
If you expect the grade to return as graded media corresponding to the export edit project, then factor in at least 2.5x the storage.
Try to avoid USB unless copying the data is not time sensitive. Otherwise there will a large dent in the schedule devoted to moving the files.
jPo
“I always pass on free advice — its never of any use to me” Oscar Wilde.