how can I connect a microtik via VPN to hotspot server initialized in another microtik
Ensure Layer 2 connectivity to the interface that the HotSpot is running on.
VLANs and Bridges is cleaner than EoIP and bridges.
If you bridge stuff on Layer 2 - put filters on the bridge so that the separate L2 segments talk to the HotSpot only and not to eachother over that bridge.