What if the task is to do this with mm10, for which you do not have MAF data in Galaxy (and importing it via table browser or file download/upload does not work)???
There are two choices for loading large data files from other public sources:
1. download the files directly from UCSC, then load those into Galaxy via FTP
2. paste the URL of the data file directly into the Upload tool (at the top of the tool panel) or into the Get Data -> Upload file tool.
The first will show progress. And both accept most compressed file formats. Note that this will only work with public datasets (UCSC's are public).
This details for how to use the second tool are in our wiki here.
The first tool has documentation that we'll be linking in, but it is fairly intuitive to use, especially after reviewing how the second one works
Thanks, Jen, Galaxy team