Player/GM having problems upload DD2TT files with the universal importer module

So I just joined the Forge but one of my players is taking over as DM. I’ve set them at GM level in Forge and in Foundry but they are having all kinds of problems uploading .dd2tt universal VTT file scenes with the Univeral Battlemap Importer module. Is there something we are overlooking?

I thought maybe it was some kind of upload limit from a Player level account, but surely giving them GM permissions would be enough right?

It is specifically a .dd2vtt file format import, exported from Dungeondraft map software.