This app was mentioned in 1 comment, with an average of 2.00 upvotes
I got it working by installing PayPal through Galaxy Apps and installing Nok Nok passport via google play
https://play.google.com/store/apps/details?id=com.noknok.android.passport2&hl=en
Then I rebooted and the option to use fingerprint ended up coming up in PayPal.
I didn't know you could use this, wonder how many other apps there are that allow this.
I also had a fingerprint registered on my S6 prior to setting all this up so I'm not sure if that also had something to do with it.