Click on Settings from the left-hand sidebar.
Click on Calendar Integrations.
Find iCloud among the list and click on the integration card.
Click on Connect iCloud.
On the Connect your iCloud account page, click on the link and sign in to your appleID.
Once signed in, and on the https://appleid.apple.com/account/manage page, click on App-specific passwords.
Click on the plus sign to add a new App-specific password to your account.
Next, provide a name for your App-specific password.
You should now have a new app-specific password showing on the screen. Simply copy this password.
Now, enter your apple ID and newly generated app-specific password in the NeetoCal's Connect your iCloud account page.
Click on save. You should be able to see Manage iCloud button.
You will now be able to see a list of calendars in your iCloud account and set your calendar preferences accordingly.
If you want to connect another calendar account, click the Add a calendar account link and follow the same steps.
If you want to know more about customizing your event preferences, please check out this article: https://help.neetocal.com/articles/customizing-event-name.