My single deployments all have that directory with a file "cas" inside it. The ls output you provided doesn't seem to contain a configured CAS server so it doesn't look like a single machine install:
ls -l /opt/sas/viya/config/etc/
total 20
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 batchserver
drwxr-xr-x. 3 sas sas 53 Nov 22 2019 cas
drwxr-xr-x. 3 sas sas 21 Nov 4 2019 common
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 compsrv
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 connect
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 connectserver
drwxr-xr-x. 3 sas sas 235 Nov 22 2019 consul.d
drwxr-xr-x. 2 sas sas 28 Nov 22 2019 deployment
drwxr-xr-x. 2 sas sas 4096 Oct 4 05:36 evmcltsvcs
drwxr-xr-x. 2 sas sas 4096 Oct 4 05:35 evmsvrops
drwxr-xr-x. 3 sas sas 20 Nov 22 2019 httpd
drwxr-xr-x. 5 sas sas 4096 Nov 22 2019 init.d
drwxr-x---. 2 sas sas 59 Jan 6 2021 licenses
drwxr-xr-x. 2 sas sas 6 Oct 22 2019 pam
drwxr-xr-x. 2 sas sas 17 Nov 22 2019 pam.d
drwxr-xr-x. 4 sas sas 34 Nov 22 2019 pki
drwxrwxr-x. 2 sas sas 4096 Oct 4 05:33 rabbitmq-server
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 sas-consul
drwxr-xr-x. 3 sas sas 22 Nov 22 2019 sasdatasvrc
drwxrwxr-x. 3 sas sas 21 Nov 22 2019 SASEventStreamProcessingEngine
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 sasgpud
drwxr-xr-x. 7 sas sas 73 Nov 6 2019 SASSecurityCertificateFramework
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 sasstudio
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 spawner
drwxr-xr-x. 2 sas sas 6 Oct 22 2019 ssl
drwxr-xr-x. 15 sas sas 232 May 15 2020 sysconfig
drwxr-x---. 3 sas sas 21 Nov 22 2019 vault
drwxr-xr-x. 2 sas sas 24 Nov 22 2019 viya-svc-mgr
drwxr-xr-x. 3 sas sas 21 Nov 22 2019 workspaceserver
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Greg Wootton | Principal Systems Technical Support Engineer