Stuck at dragon ruins

I have made my way to the dragon ruins but the path is blocked by a sign saying dragon ruins closed. I have already beaten the selene City gym leader so I don’t know what to do next. Please help.

Where do you see the sign?

Hello! You have to defeat Taen in the dragon ruins up above where the sign says it’s closed. After that it should open up, if you’ve already defeated him then I’m not sure.

Defeat Taen first.