Hi,
As you say the phone may have a virus or malware installed.
Download, install and then run either of the following programs and check the results.
[https://play.google.com/store/apps/details?id=com.avast.android.mobilesecurity&hl=en_AU|program 1]
[https://play.google.com/store/apps/details?id=org.malwarebytes.antimalware&hl=en_AU|program 2]
Once you’re satisfied that the phone is now virus or malware free there are some settings in the phone that may prevent apps from downloading in the background without your permission.
Here’s a image taken from the [https://www.helpforsmartphone.com/public/en/samsung/galaxy-s10e/android-9-0/manual?pageNumber=155&query=user+manual#1|user manual] that shows the settings.
[image|2135875]
(click on image to enlarge for better viewing)