iphone 3g 32 uppgradera

No, sorry but the max. iOS version for the 3Gs is iOS 6.1.6. You cannot update it any further.

I would try to on your computer use iTunes app store and download the app

this tie it to your appleID

then on the phone go to app store and purchases->not on this phone find the app

and try to download the lastes supported version read more

Install the latest compatible version of an app on an earlier version of iOS or OS X - Apple Support