I was just about to mention that as well. I forgot what error I was receiving on Windows 10 but it was indeed due to MSCHAPv2 not being checked.
Here is how I have mine setup on Windows 10 (Anniversary Release)
Created connection in the Windows 10 GUI then opened network adapters and changed the properties as shown in the images below. This is working with me as well as a buddy of mine who connects up as well.
Exact CLI used for initial config (I have two static IP addresses, however my ISP assigns my public facing which is why you see the interface "pppoe0".
I essentially used the tutorial previously posted https://help.ubnt.com/hc/en-us/articles/204959404-EdgeMAX-Set-up-L2TP-over-IPsec-VPN-server and modified for my setup.
configure
set vpn ipsec ipsec-interfaces interface pppoe0
set vpn ipsec nat-traversal enable
set vpn ipsec nat-networks allowed-network 0.0.0.0/0
show vpn ipsec
set vpn l2tp remote-access outside-address 72.16.xx.xx
set vpn l2tp remote-access client-ip-pool start 172.16.4.20
set vpn l2tp remote-access client-ip-pool stop 172.16.4.30
set vpn l2tp remote-access ipsec-settings authentication mode pre-shared-secret
set vpn l2tp remote-access ipsec-settings authentication pre-shared-secret hardPSK123
set vpn l2tp remote-access authentication mode local
set vpn l2tp remote-access authentication local-users username testuser password testuserpw
set vpn l2tp remote-access mtu 1492
set vpn l2tp remote-access dns-servers server-1 172.16.2.1
set vpn l2tp remote-access dns-servers server-2 8.8.8.8
commit
show vpn l2tp remote-access
Firewall policies in the GUI for "WAN_LOCAL" or whatever you have it labeled as.
The two added are "Allow L2TP" and "AllowESP", I had allow ESP first which would cause the VPN to not connect.