Its not complicated at all. For one its a paid service so if you can afford it do it. If you wanna do it free you have to host it yourself
- Get a Calendar app that supports CalDAV, Task app that supports WebDAV.
- you make calendars and task lists in etesync dashboard
- copy their links and paste them in the app settings of your calendar and task apps. It also supports cardDAV for contacts
Thanks for the context, i got curious and read halfway through the junius pamphlet cause of that