Opening Itunes from an external hard drive stuck loading

I'm trying to open an itunes library from an external hard drive, but it's just been stuck loading.

I use an external hard drive for itunes with an old mac book and am able to open and use it fine there. However, I'm trying to use that same itunes library on a new mac book and am not able to open it. So far I've:

• held down option and selected the music app
• selected Choose Library
• selected the "iTunes Library.itl" file from the external hard drive
• it then asks me to save it somewhere. I'm not sure what exactly this is doing, but I originally let it save it in the default location (/User/Music/Music 1) and then tried again saving it on the external hard drive in the same folder as the .itl file.
• After I do that, the music app opens and I just see the loading wheel with "Loading..." below it.

Is there some step that I'm missing or does it normally take a long time to load the first time and I just need to keep waiting?