I have tried to setup Hotspot with User Manager in same MT machine , and I tryed different configuration samples, but in the end I didn't find the proper solution, the main reason in the end was maybe the 400 users load which I thing is too much.
Now I am trying to find solution where I can setup PPPOE Server in Mikrotik Machine and also NAT them in same machine.
Also I will have several profiles of users with different rate-limit, for example 128/128, 256/256, which I didn't see in user manual.
Can anybody try to help with sample config file, or try to send some ideas.
The simple diagram of connectivity is this

WAN --> Mikrotik PPPOE Server/NAT --> Cisco 3640 -->CMTS--> Clients

Thanks in advance