ReadyNAS 628 Virus definitions not loading

A few days ago I activated the antivirus on my encrypted ReadyNAS 628 under OS 6.10.3. This resulted in a never ending series of errors in the logs:

System: Antivirus scanner definition file update failed due to download failure. Check your Internet connection.

Based on previous threads I used SSH to see what was going on.

I ran

   freshclam

and got

   ClamAV update process started at Mon Jun 15 11:24:08 2020
   WARNING: Your ClamAV installation is OUTDATED!
   WARNING: Local version: 0.100.2 Recommended version: 0.102.3
   DON'T PANIC! Read https://www.clamav.net/documents/upgrading-clamav
   Downloading main.cvd [100%]
   ERROR: Verification: Can't verify database integrity
   Trying again in 5 secs...
   ClamAV update process started at Mon Jun 15 11:30:42 2020
   WARNING: Your ClamAV installation is OUTDATED!
   WARNING: Local version: 0.100.2 Recommended version: 0.102.3
   DON'T PANIC! Read https://www.clamav.net/documents/upgrading-clamav
   Downloading main.cvd [100%]

   (this repeats several times)

Looking in /var/lib/clamav there was a .tmp file and mirrors.dat but no main.cvd file.

Based on some reading I manually downloaded and installed the database files:
   daily.cvd
   bytecode.cvd
   main.cvd
I downloaded those three files, moved them to /var/lib/clamav, changed their ownership to clamav:clamav, and changed their permissions (chmod 644)

Now when I run

   freshclam -v

I get this somewhat better looking result:

   Current working dir is /var/lib/clamav
   Max retries == 5
   ClamAV update process started at Mon Jun 15 15:04:33 2020
   Using IPv6 aware code
   Querying current.cvd.clamav.net
   TTL: 568
   Software version from DNS: 0.102.3
   WARNING: Your ClamAV installation is OUTDATED!
   WARNING: Local version: 0.100.2 Recommended version: 0.102.3
   DON'T PANIC! Read https://www.clamav.net/documents/upgrading-clamav
   main.cvd version from DNS: 59
   main.cvd is up to date (version: 59, sigs: 4564902, f-level: 60, builder: sigmgr)
   daily.cvd version from DNS: 25844
   daily.cvd is up to date (version: 25844, sigs: 2622498, f-level: 63, builder: raynman)
   bytecode.cvd version from DNS: 331
   bytecode.cvd is up to date (version: 331, sigs: 94, f-level: 63, builder: anvilleg)

So, if I read this correctly, my executable is out of date but my databases now are acceptable.

1) Should I leave well enough alone and call it a win?

2) What's the recommended way to get clamav up to date?

3) What went wrong in the first place on what is basically a new system?