I got the 1st coin separately. The 2nd is the easiest and the 3rd contains a complex timing.
1st coin : get 5 mini coins and enter the hidden portal, then in x2 small wave click 23 times very constantly. I guess I've succeeded within 20 trials. If possible, be sure to hear the click sound.
Hiroquet presently has 167,239 views for Geometry Dash across 2,149 videos, and over 3 days worth of watchable video for Geometry Dash published on his channel. This makes up 82.83% of the content that Hiroquet has uploaded to YouTube.