I'm confused... Can you help me to understand your problem? On my Android phone (with the Gboard keyboard), I just copied something. Then I went to this box on G2G (the editor on this page). Tapping into the box, the virtual keyboard came up. There, the central first thing at the top of the keyboard was the paste icon. I hit that and it pasted the text into the box. I've just gone back to it now and the paste icon is not there, but it's two taps away (on my phone). The clipboard icon is top-centre of the keyboard. I hit that and it has my clipboard history ready to paste into the box. If the clipboard icon is not there, there's a thing with four little squares in the top left. Hit that, then 'Text editing', and there's a paste button.
What's the problem...?