Ah, i see the problem. You need to copy the file /opt/omd/versions/2.0.0p17.cre/lib/python3/cmk/base/plugins/agent_based/cisco_wlc_clients.py to /opt/omd/sites/<sitename>/local/lib/python3/cmk/base/plugins/agent_based/cisco_wlc_clients.py.
From the file you just shared delete anything after your comment
Inside the file /opt/omd/sites/<sitename>/local/lib/python3/cmk/base/plugins/agent_based/cisco_wlc_clients.py you need to adjust the line
detect=matches(OID_sysObjectID, r"^\.1\.3\.6\.1\.4\.1\.9\.1\.2530"), accordingly as i mentioned in post #8 (should be around line 66).