RPG Maker MV is essentially a custom browser designed to play rpgmaker mv games. It uses a library called Pixi.js which references WebGL. I am unsure as to why you would be seeing this error however... RPG Maker MV's engine should not have this problem with WebGL not being supported
Viewing post in Tagaia Chronicles Early Demo comments
Update 9-14-20: Relatively recently I got Itch.io App working on my linux computer. Through fiddling with another program I found out that your RPG Maker game and some other apps will only work if installed and ran through the Itch.io App. So I tried installing and running yours through the Itch.io app and it worked. I've already played through the demo and I really enjoyed it. Well done. Did you make the assets yourself or was it premade assets? I'm fiddling with RPG Maker MV myself through steam, so I'm just curious.