Hi @mopac welcome to the /e/ forum.
I currently have two devices on /e/ which I think were earlier built than S7, I would not assume that as your main problem.
However it is very unfortunate that Samsung had a little hiccup in development at LineageOS (from which /e/ is forked) a while ago. This may in part be behind the serious lag in development of https://doc.e.foundation/devices/herolte. Worse, there is talk, in development-updates, that this generation of Samsung may be dropped due to lack of an /e/ ROM maintainer; even though there are active ROM maintainers at Lineage. 
/e/ and microG take a bit of getting used to and one has to want the device to be as free as possible of Google even if all highly over-networked activities are not possible.
I like to only install trusted apps, in the first instance I check the https://reports.exodus-privacy.eu.org/en/ report in Apps or App Lounge or just look up online.
A search for Paypal https://community.e.foundation/search?expanded=true&q=paypal will give some clues.
File app lettering may be associated with your language, German has had some issues fixed for v1.0, coming very shortly; which language are you using?
For specific errors always check https://gitlab.e.foundation/e/backlog/-/issues
If unresolved please do ask again with specifics. 