Enable a read-only SNMP v2c community (or v3 user) on Cisco IOS and IOS-XE, then add the switch in Zynty.
Connect to the switch and enter configuration mode. Use a community string that isn't "public" or "private", and restrict it with an access list if the switch supports it.
enable configure terminal snmp-server community zyntyRO RO snmp-server location "Branch - Lyon" snmp-server contact netops@company.com end write memory
If your policy requires authentication and encryption rather than a plaintext community string, configure an SNMP v3 user instead.
configure terminal snmp-server group ZYNTY-RO v3 priv snmp-server user zynty-ro ZYNTY-RO v3 auth sha AuthPass123! priv aes 128 PrivPass456! end write memory
From the collector's network segment, a quick SNMP walk confirms the switch is responding before you add it in Zynty.
snmpwalk -v2c -c zyntyRO 10.20.6.10 sysDescr.0
Use SNMP v2c (or v3, matching what you configured) as the protocol, and enter the community string or v3 credentials exactly as configured on the switch.