Minimum requirements-
At least Android 5.0 Lollipop on your Android phone running WhatsApp version 2.22.7.74 or later
IOS 15.5 running on your iPhone with WhatsApp version 2.22.10.70 or later
The iPhone should be factory reset or should be fresh.
Both devices should be on the same Wi-Fi network.
These are some of the requirements which are necessary or else the Move to IOS app won't pair.
The official WhatsApp support page can be found here.