Hello Rune,

Thanks for reaching out to us. Please find the answers below 

1. Event Booking with Calendar Integration: Ability to book courses and automatically add them to participants' calendars, such as via iCal.

Amelia already has this option, but, unfortunately, the integration with ICal is not available at this moment. We will add this in future updates, but currently, Amelia can be integrated with Google and Outlook Calendar. More information on this link.

      2 . Payment Integration: I need to process payments securely, preferably through Stripe.

This is already integrated, you can use payments such as Stripe, RazorPay, WooCoomerce, Mollie and PayPal. You can find more information on this link.

      3. Participant Communication: It’s essential for me to communicate with attendees directly through the system, sending confirmations and reminders.

This is configured by default, the confirmation emails are sent to both customers and employees depending on the appointment status. Reminders can be also configured with WP cron (WP control)

      4. Automated Material Delivery: I would like to send materials to attendees automatically, a specific period before the event begins.

Unfortunatelly, there is no dedicated option for this, but you can use emails for this purpose. You can add some links in notification templates as they would see them depending on the appointment statuses.

     5. Customized Information: Ability to provide custom information, such as refund policies and additional terms, during the booking process.

This can be configured with custom fields. 

The Custom Fields feature gives you the option to add more fields to your booking form so as to customize it to best match your business needs. The customer’s first and last name, email address, and phone number are there by default, but with the Custom Fields feature you can add extra fields if you want to ask a customer a question, collect additional personal details, or for any other reason.
For appointments, these fields will appear on the Booking form under the default fields, and once your customer fills them this information will be shown in the appointment information on the back-end. Here you can find more information.

I would also recommend starting with a standard license since this would have all the options requested before, but if you need any other features, you can always upgrade later.

I hope it helps.