Error with anti-virus app?

The logs show repeated message of

[files_antivirus] Fatal: OCA\Files_Antivirus\BackgroundJob\BackgroundScanner::run, exception: The antivirus executable could not be found at /usr/bin/clamscan

at 2019-02-17T14:45:05+00:00

What needs to be placed and where in system. Running nextcloudPI version 15

The message says all, the ClamAV package seems not to be installed. Install it!