[SOLVED?] Steam / external hard drive issues with Launcher

Deveros

So I've had ESO for a year or so now and with the Morrowind update I knew I was running out of space on my laptop and would have to be put it all onto an external hard drive with the coming Summerset updates.
My issues stem mainly from not being able to go beyond the "loading.." in the launcher. I've already installed the latest version of ESO from steam onto my external, which is a seagate 2 tb 3.0 usb, and I have a relatively recent version of it just on my internal hard drive. I can't tell if it's an issue with Steam either because from the steam properties for ESO it doesn't allow for me to verify the integrity of the files as it's just blacked out. This hasn't ever been an issue with any of the other games I've gotten and downloaded through steam and just seems really odd.
I've done some looking and while some discussions seem to just end up working for people, I've been at it for a few days and was really looking for some help.
I'm running off High Sierra v10.13.5 on my MacBook Pro 2015.

Thanks in advance.

Deveros

So I sorta "fixed" it by not downloading through steam and just getting it onto my external, and then in the Zenimax Online folder just opening the Elder Scrolls Online app rather than the launcher and that seems to have worked?

It's kinda awful in all honesty and I just wish this worked through steam but oh well.