Webpanel to domain installation

i have a domain ex domain.com
nginx already configured for SSL with certbot
so im getting an error on pritunl that 443 & 80 port already taken (nginx)

i dont wanna use another random port cause it doesnt have SSL
i want to access pritunl with https://domain.com/pritunl
how to do this?

The load balancing documentation has information on changing the servers port.