Are we to upload the externalredirect.php file? You didn't specify this in your instructions.

If so, to where...the forum root?

I have this installed...yet I'm not receiving the redirect message when going to an external link.

Yes, upload externalredirect.php to the forumroot.

Enable the plugin in Vboptions - > vboptions all the way at the bottom.

There is no option to enable the plugin in Vboptions - > vboptions.

set the buttons to yes,

I have nofollow set to no, then the rest to yes

I do not currently have this marked as installed...since I can't get it to work.

I have made the file edits as posted in your readme file.
I have uploaded the externalredirect.php file to the forum root.
I have installed the product.
I found your product in vBoptions and have the following settings:

• Use no follow attribute is set to "no"
• All other settings are set to "yes"

I'm not getting any redirect message at all.

I had this same issue, I eventually got it working by rebuilding post cache.

If posts and things are cached then you would need to rebuild the caches for the edits to take place.

I just rebuilt the post cache...guess what?

It's still not working...

not sure then, wait for the mod author to respond I guess,.