A starting prompt
Paste this into the builder and change the names, rules and colours to yours. It produces a working first version; everything after is refinement.
Announcements first
Every community app is an announcements feed with extras. Put the feed on the Home tab, newest first, with a date and an optional image, and make sure the people who run the group can post without touching the app. The prompt above does that with a Google Sheet: a row is a post, publish the sheet as CSV, and the app reads it on launch. Anyone who can edit a spreadsheet can now update the app.
Events that land in calendars
An event list is only useful if the date leaves the app. "Add to calendar" on each event inserts it into the phone's calendar with the place and a reminder. Ask for it — it is a one-line request that makes the Events tab worth having.
Media without hosting
Talks, recordings and podcasts should stay where they already are — YouTube, SoundCloud, a podcast host, Google Drive. The app lists them with a title and date and plays audio in a built-in player or opens video in the host's app. No storage, no bandwidth bill.
Donations and payments
Do not build donations into the app. Link out to the donation page you already have (a payment provider, a bank link, a charity platform). It is simpler, it keeps you clear of Play's payment policies for non-profits, and it means the app has no financial data to protect.
Notifications
A local notification fires when the app notices a new announcement in the sheet (it checks on open and periodically in the background). If you need true instant push for hundreds of members, set up Firebase or OneSignal in the builder's Push panel and ask for push notifications.