On an iPhone/iPad there are two ways to manage your Google Calendar. You can either use the Google Calendar app and view the Flatirons calendar in that app. This is the easiest way.
Or
You can use the existing built in iPhone Calendar app (this is desirable if you want to see Flatirons events on the same calendar as your existing iPhone calendar, but it is more difficult to set up)

Directions for both techniques are below.

 

Instructions from Apple are here   Scroll down to the section entitled “Subscribe to a Calendar”.
For your convenience, here are the steps from that Apple page:

1. Go to Settings > Calendar > Accounts > Add Account > Other.
2. Tap Add Subscribed Calendar.
3. Enter the URL of the .ics file to subscribe to
Note that this calendar setup on your iPhone/iPad will require 2 steps that some people find challenging on a phone – you need to copy the url of the “server” of the calendar then paste it into the calendar settings.

Here  is the server url:
(Note that while this looks like a website link, it is not clickable. It is intended to be copied and pasted into the Calendar app settings.)

https://calendar.google.com/calendar/ical/e3g4orq9b143eglfr2gv0lmqp4%40group.calendar.google.com/public/basic.ics

**For ease of setup, before you start the calendar setup as detailed in the Apple page, first copy the server location as it is shown above. Copying on an iPhone is done like this: First you select the text by tapping and holding on it until the little blue selection bars appear, then drag the bars so that JUST your server location is selected in blue. Then tap “Copy” . See example:

Then follow the steps in the Apple directions. When you get to step #3 in that process, which they have over-simplified by saying “Enter the URL of the .ics file to subscribe to”, you need to paste the content you copied. Tap and hold on the spot you need to paste to. When the “Paste” option pops-up on the screen, tap it and it should insert the content that you copied earlier.
This process can be challenging when you first try it, that’s why we called it the “more difficult option”. But the integration of the Flatirons calendar into your existing calendar may be worth the trouble.

The phone manufacturers have a lot of latitude to modify the software on Android phones, so not all of them require the same steps to add a calendar. Here are general directions:

Go to the Flatirons calendar   https://www.flatironsvbc.com/calendar-2021/  and click on the  blue and white “+” sign under the calendar.

It will go to the Google Calendar page and should log in automatically with your Google account.

It will show a dialog box asking if you want to add the Flatirons calendar. Click Add, and the calendar will be automatically added.

In the future, you can find the calendar by going to any Google page (Search, Gmail) and clicking the Google Apps icon (9 dots) in the upper right.

If after doing the above, you open the Google Calendar app and the calendar you just added is not displayed, you will need to tell the app that you want the Flatirons calendar to be displayed.
You will see a list of the various calendars that you have subscribed to on the left side. Put a checkmark next to the calendars you want displayed. (You may need to tap Show More to see the checkbox that you are looking for.)

Many people find it easier to use your computer to subscribe to the calendar, and then you will see it appears on your phone. Here is a link showing that process:

Some general info on using the Google Calendar on an Android phone: