I also connected GoPlus 2 to M5 Basic.
Next, I connected Relay Units to PortB_1 and PortB_2 respectively and confirmed the operation.
UIFlow Block is based on the image posted by ajb2k3_san.
I didn't have to use a block of Relay Units.

@lgx
Thank you for your reply.
From your information, I knew that it was a Core 2 feature.
I want to use 4-Relay with my M5stickC.
I will continue to study UIflow.

Thanks for the great information.
And I have a question.
Is the block in the second half of the last figure a block for 4-Relay Unit?
My UIFlow (ver.1.7.3) doesn't have a 4-Relay Unit icon, so I can't select it.

I am suffering from a similar problem.
I tried to use Pa.HUB to use two Light sensors in addition to the M5 Stick C + UIflow.
However, even if unit can be selected, HUB does not appear in the menu for selecting Port.
Please let me know if there is a solution.