Can't I define aliases (using `export`) that are in my current directory? Doing so gives a `not found` message

TLDR: have to define an alias/variable using the export command, I can't use the full path and using a relative path (i.e. defining the alias while in the directory directly above what I want to assign) gives a Not found error. Anything else I can do?

I have to run these two commands:

export FREESURFER_HOME=/usr/local/freesurfer

source $FREESURFER_HOME/SetUpFreeSurfer.sh

Except the system is not my own, so I don't have permission to /usr/local/freesurfer . So I improvised and installed the program called freesurfer elsewhere (the full install path is /Raid6/users/bob/Downloads/freesurfer).

So I've been trying to set the alias FREESURFER_HOME to the freesurfer directory (I need to do this step because the SetUpFreeSurfer.sh file assumes its defined and uses it.

When I use the full path like so: export FREESURFER_HOME=/Raid6/users/bob/Downloads/freesurfer and then type $FREESURFER_HOME and press enter, I get a "Permission denied" error.

So I navigated to my Downloads directory such that typing ls would list, among other things, the freesurfer directory. And then I try export FREESURFER_HOME=freesurfer, but after I do that typing $FREESURFER_HOME and pressing enter gives me the message freesurfer: not found.

Not sure what to do/try from here, any help is greatly appreciated!