I am not connected to Enterprise right now, but perhaps there is a hard limit on file to drag and drop. This space is intended for smaller files.
The better alternative in Enterprise/Desktop is to place the files on a network share and then set up a connector to the share. There will be no hard limits on the file size -- disk space and RAM will be the limits.
Logic will get you from a to b. Imagination will take you everywhere. - A Einstein
In general, if you want to load files, good to place it onto a folder in the drive rather than doing like this way. Create a data connection and specify the path. The service account which you are running Qlik Sense Services need to have privilege to the folder.