Wd my book world 2

Hi guys… i really need some detailed help here…
I took a 10 year old device from my uncle… i was able to update a firmware… and i can see the drive on network…i can access the admin page too… wht i need help with is…
1- wht softwares with a file browser like interface use this for windows 10 and mac to access the files in the folder?
2- how do i setup the back up system? With what apps? i tried good sync, doesnt work too well.
3 most importantly how do i access it from an external network? None of the wd apps seem to work…
4 how do i access from iphone??
Guys i know it is a 10 yr old device… but i m sure i can find ways to make the most of it?
Point 3 and 4 are most important. The app listed in the admin page for external access is not supported any more… what 3rd party apps ca i use for backup, and external access?

Guys… using it like a FTP within internal network… i am behind ISP NAT, so cant port forward, also dont want to keep a computer running 24/7… experts pls help… how do i setup access outside my network?