Error 500: During activating the plugin

A 500 error is mostly caused by a plugin and/or theme clash. So there is no fixed way to solve it.
Please change your theme to any of the default Twenties. Then deactivate all plugins, except for Events Manager and EM Email Users.

Is that setup works, activate each plugin one by one to see which one is causing the error.

Thanks. I also thought the same. I’m using your payment gateway selector plugin without any issue. I wish this plugin will also work but seems my child theme is not accepting it.

Right now it’s not possible for me to switch to different theme and test with other plugins as it will take some time. I’ve other workloads. Hopefully, it’ll work from next release. Also, if I get free time will go through the switching process.

That’s fine.
When you do start to test, please make sure you put WordPress in Debug Mode first. Else there will be no errors written to the debug.log file in wp-content, making it almost impossible to track the error. ??