If you add a time event with "Open Web Link" and the users have a pop-up blocker enabled in their browser, the external website will not open. (This does not apply to interaction events, only to time events).
If the link does not open (even with an interaction event), it is probably related to an iOS mobile device limitation. When the VR project is displayed on iPhone or iPad, the iOS system blocks opening new websites. When displayed on Android or on a laptop, there should be no problems with interaction events and the use of the Open Web Link function.