Help needed: First steps to route thru VPN

I am completely new to RouterOS and hope I could get some help for the first steps.

This is what I would like to achieve:

have a MicroTik router connect from within a private network, via VPN to an other router accessible via the internet
have clients that are connected to the MicroTik router access computers on the private network the VPN connects to

The setup is as follows:
Network A: 192.168.0.0 – gateway 192.168.0.1
MicroTik router WAN connected to Network A 192.168.0.50
devices within IP Range 192.168.88.0 – Gateway 192.168.88.1 connected to MikroTik router

Router at Public IP: ww.xx.yy.zz
Network B: 192.168.1.0 – gateway 192.168.1.1
eg Server: 192.168.1.40

What I already could manage is a L2TP connection from the MicroTik Router (inside Network A) to the public IP of Network B. I am able to access the internet from devices connected to the MicroTik router and connect to devices on Network A (one downstream). But I am unable to connect to devices inside Network B, like Server 192.168.1.40, even though the VPN is running.

I understand that I have to make a static route to tell all packages for 192.168.1.x to go thru the VPN, but I don't seem to be able to get that to work. Maybe there is more I have to do, but I couldn't figure it out.

Any help is appreciated.

aug/14/2020 23:42:15 by RouterOS 6.47.1

software id = 4H13-CSI8

model = RBD52G-5HacD2HnD

/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=default-dhcp disabled=no interface=bridge name=defconf
/interface l2tp-client
add connect-to=ww.xx.yy.zz disabled=no keepalive-timeout=disabled name=sas-l2tp-out1 password=+++ profile=default user=+++
/ip address
add address=192.168.88.1/24 comment=defconf interface=bridge network=192.168.88.0
/ip route
add distance=1 dst-address=192.168.1.0/24 gateway=sas-l2tp-out1