So I'm switching back to it from my current Moto G4 Plus because I like the Note 3 A lot but it won't install any apps from play store as it shows as a test 13.5mb/13.5mb and it won't finish
13.5mb/13.5mb? Or 13.5GB/13.5GB?
If 13.5mb/13.5mb, you probably don't have enough space to install any apps.
And if an app is already installed, you can't install it again. You can update it if the "Install" button says "Update", but you can't install an all over itself.