Problem with url, many participants complain about experiment crashing

Url: perceptionTASK [PsychoPy]
Please help!!

I uploaded my experiment weeks ago to Pavlovia, after checking that it worked well on my laptop on diverse browser. Until the first 8 participants everything was fine. Afterwards 2 with MAC had issue with the url. It was just not working. I recommended them to open it to another browser one could with Chrome the other only with Firefox. They run it, everything was fine. During the same day I had 2 participants with windows complaining that their browser (Chrome) crashed, and one of them even said that the experiment made her computer crash when she used the esc button. I deactivated the experiment, to check the settings, but I couldn’t found the reason for these errors. I activated again and asked one participant to test it and everything was back to normal.
Today my supervisor shared the url to one of her classes, and the participants addressed multiple errors (40 participants run the experiment simultaneously). Not a single one could complete the experimental task, because it either crashed in an unexpected time or it was not opening.

I am trying to understand what is wrong with the experiment. The experiment is 16 min long and has 80+ videos. Maybe that might explain these technical issues? Is there a limitation in the number of participants that can run the experiment simultaneously?

Thank you in advance