How to play on Wynncraft with Shader?

I got Optifine HD for the 1.12.2 to play with shaders (I tried the Sildur shader).
In Singeplayer worked without problems.
But when I just wanted to join Optifine on Wynncraft my Minecraft is greasy because my mod is not allowed.
But how do all the creators manage to play Shader on Wynncraft?
See videos like "Wynncraft with Shader".

Would be glad about help.
Maybe you can try it. Time out.

Do you have only optifine installed or others. Optifine is available as a "mod" file or simply as a jar.

with the jar file that works flawlessly

I solved the problem. Thanks for the answer. Because of the fact that there are several versions of Optifine for the 1.12.2. The one I tried was blocked.