I think you are out of luck here. A servo requires a PWM (pulse wide modulation) signal, however the three B ports on the GoPlus2 are only good for simple input and output signals but cannot do PWM.
The GoPlus2 description reads: Three PORT-B interfaces(Analog Input,Digital Output,Digital Input) can be expanded.
And looking at the GoPlus2 blocks in UIFlow the digital output can only be set to 0 or 1, but nothing like PWM.
Thanks, that's what I want to know. I'll use the B Port in the M5Go base instead. Thank you so much.