I read F5 documentation and looks Overlay needs to enable SND service. I doubt that licence key is the cause.
root@(host-192)(cfg-sync Standalone)(Active)(/Common)(tmos) show sys license
Sys::License
Licensed Version 11.6.1
...
Active Modules
LTM, Lab, VE (FPYNJUP-NVRYDZA)
IPV6 Gateway
Rate Shaping
Ram Cache
Client Authentication
Application Acceleration Manager, Core
SSL, VE
Max Compression, VE
Anti-Virus Checks
Base Endpoint Security Checks
Firewall Checks
Network Access
Secure Virtual Keyboard
APM, Web Application
Machine Certificate Checks
Protected Workspace
Remote Desktop
App Tunnel
root@(host-192)(cfg-sync Standalone)(Active)(/Common)(tmos)