Hi nguyendai26,
Please make sure you add a public group permission when creating your pipeline.
Also ui problems are normally down to conflicts with other media players installed on users themes we will rectify this with the next release.
If you activate the basic WordPress theme you will notice the ui should be fine it should look like below.
https://s3bubble.com/s3bubble-hls-streaming-demo/
In Chrome right click and inspect element this will open the developer tools go to you network tab and then refresh the page and it should should you the errors you are getting.
It will normally be a 403 permission denied error meaning you need to set the permission group when creating your pipeline.
We offer consultancy at a day rate if you are interested please contact support@s3bubble.com
Best Regards
S3Bubble