There are a few steps to getting this to project to build, and it's unclear why this would have worked in earlier versions of Unity.
1. There are some compilation failures due to incompatibilities with newer versions of TMP. Luckily, these only exist in the `Assets/TextMesh Pro/Examples & Extras` folder which can be safely deleted.
2. The project makes use of UnityEngine.Ping in `Assets/Scripts/PanelEstado.cs`. Ping is unsupported on the web, however I can't find any official documentation indicating that. The relevant code just updates a ping with a coroutine, and that can be safely commented out as a workaround.
3. Some external functions are declared in `Assets/Scripts/NativePluginLoadImage.cs` but appear to be iOS specific - their calls are wrapped in a preprocessor flag that excludes them if the platform isn't iOS. Wrapping the declarations themselves in the same preprocessor flag solves this problem.
With those three fixes, I don't see any obvious problems. The project builds and runs locally.
Here's a link to a forum post where the lack of Ping and workarounds are discussed:
https://forum.unity.com/threads/ping-meter-for-webgl.412794/