Can't install f-droid or other APK (except from google) on lineage 19

[lmjst]

Hi, I can’t install .apk from repo outside of google store. I’ve tried f-droid, aurora, without success.
My phone is a nokia 7+ with lineage 19.
Can I post further details and captures here for help ?
Thanks

PS This is my first smart phone with android, bear with me…

[SkewedZeppelin]

What error do you get?

Where did you install gapps (Google Apps) from?

[lmjst]

Thanks for your response.
Sometimes I got no notification at all, just nothing happens, sometimes I got “package installer kit automatically stopped”

Google was installed when I bought the phone.

Some captures if this may help:

[SkewedZeppelin]

You need to find a proper OS, not an unofficial pre-release build of LineageOS.

[lmjst]

OK thanks I’ll look to find something compatible and with a smooth install learning curve.

[Lyrics7151]

Did you buy the phone with that ROM preinstalled? If so I would definitely reflash anyways. Would be a bit dodgy if they weren’t even selling a proper lineage version