In addition please refer the following guides also :
http://www.cisco.com/c/en/us/td/docs/wireless/access_point/3800/quick/guide/ap3800iepgetstart.html
If you have an existing WLC you can configure it on WLC.
For other config options please refer the following Guide:
http://www.cisco.com/c/en/us/td/docs/wireless/access_point/1850/hardware/guide/ap1850hwguide.html
Can you check the following :
1.NAT exemption rule for the VPN clients
2. Please check that if the ACL is not dropping the clients.
Please check the following link also;
http://www.cisco.com/c/en/us/support/docs/security/asa-5500-x-series-next-genera...
