If your App Link doesn't work, what you are seeing may be related to a configuration on your own device.
Please follow these steps:
1. Could you try to disconnect from the WIFI network and use LTE?
2. If still doesn’t work , make sure that your default browser is set as Safari.
3. Sill not working? Check if you have an "active content" blocker on your phone and disconnect it. (Check here how to enable/disable content blockers on Safari —> https://www.macrumors.com/how-to/enable-content-blockers-safari/)