The link on the calendar page tries to automatically add a subscribed calendar to your phone or tablet.  If you are having issues you may try the following.  The instructions here have been able to resolve most issues.

If you are using a Google calendar try this option:
Trying clicking on this link to subscribe to all events :  http://ics.teamup.com/feed/8dc6ae7d8589d91fe510027b181d66184bbb447f/ks90562653e998e80e/0.ics
If you continue to have issues you can try to add a subscribed calendar manually.  Go into the settings on your phone for your calendar and past the link above in the settings.  You can also go into your Google account from a desktop or laptop and subscribe from there.

All other calendar types:
Trying clicking on this link to subscribe to all events :webcal://ics.teamup.com/feed/8dc6ae7d8589d91fe510027b181d66184bbb447f/ks90562653e998e80e/0.ics

You may also go into the settings on your mobile device and add a subscribed calendar manually.  Go into your calendar settings on your device and try to add a subscribed calendar manually.  Copy the link into your settings to subscribe

Yes.  You can subscribe to specific calendar categories. Make sure you select the correct ones so you don't miss out of events.  Here are the individual subscription links (Scroll down for Google calendar Options):

Below are the links if you use a Google Calendar