Most devices take you straight to the Facebook app, or the mobile version of Facebook, when you click on their links. But there are certain settings that you can only access on a desktop version of Facebook (like what you would see on your computer), including editing group settings to add PostMyParty as a trusted app.
Check this video and give it a try (no audio):
The easiest way I've found to access the desktop version of Facebook on an iPhone Safari browser:
1) First log out of your account.
2) Then click the "Aa" on the upper left side of the browser URL field for more options and click "Request desktop site".
Make sure it changes. You might need to try a few times, by going back to mobile site then requesting desktop site again, etc.
3) Log back into your account, and continue using normal instructions for Desktop Facebook.
Find your Groups by clicking the menu:
Other notes if you still have trouble:
If you close your browser and come back in, it may automatically convert back to Mobile site and you will have to do this over.
If you get a notification from the FB app saying someone has tried to log into your account, click it to back into the app and confirm that it was you. Remember to switch back over to your browser to continue.
Try manually inputting your user email and password, instead of the saved info.- Go to your phone settings and clear the cookies and history for your browser, and/or restart your device and try again.
Try logging out first, then remove the "m" in the URL website address in the browser field and replacing it with www, like this: http://m.www.facebook.com
Sometimes trying from a Private browser helps.