Hi,
the problem is not with your DHCP server, but in your AP's configuration, I suppose.
That configuration (AP with 1 vlan and 1 mikrotik) is very common.
Why do you have in your config a static getaway and dns?
ip domain-name ngtrain.com ip route default 192.168.88.1 ip name-server 1.1.1.1 ip name-server 9.9.9.9
Why do you have this?
interface portchannel 1 switchport mode access switchport access vlan 1 !
What I would do: reset anything to default, it will works.