VpnCilla is a VPN App of type "IPSec XAUTH PSK" in the variant IKEv1in agressive mode and this variant of IPSec is long outdated.
If your VPN server supports a more recent VPN as eg. IPSec IKEv2 or even better Wireguard, you should uses this and a corresponding VPN Client and not VpnCilla!
So in case your VPN Server supports Wireguard you will find the original Wireguard Client App for free at Google Play Store: play.google.com/store/search?q=wireguard&c=apps
If you are really aware of the security risk by using VpnCilla, you can download the latest VpnCilla APK here for free: vpncilla.apk