Using iCalendar RRULE Repeater Options (BETA)
There is undocumented feature in the repeater that is still in beta allowing you more complicated repeating options, but you can use it successful .
Go to the event and click Set Repeater button and this popup will show up:
Now the option I will give you is quicker, but as I said undocumented yet. Click on the popup (anywhere also the form should be rested no checks or options selected) and press CTRL + ALT + SHIFT+ R and the popup will change into this:
In the first input RRULE String paste the RRULE generated from this website: https://icalendar.org/rrule-tool.html