Thanks for your quick response!

Just tried to download MRIcroGL on a different browser - still didn't work. It said (Error 2 - no such file or directory). 

Also sending a screenshot of my terminal and the error I am receiving when I try the command. The left window shows the receipt of the software download - or so I thought. The right window shows the error I receive when I try to use the dcm2nii command.