Payments / MailChimp / CRM for a neighborhood association?

I’m trying to simplify things that take way too long for our neighborhood association to do. (It's not an HOA, just a group that plans events and manages a security patrol, and all fees are voluntary.)

Basically, we have several different systems for managing communications and payment. This creates a mess for tracking and keeping information up to date. We are looking for a solution that will be as inexpensive as possible and will ideally not take a cut of any payments we accept.

What we’ve got right now:

1. MailChimp (free level) with individual subscribers. Neighbors join through a webform.
2. Excel sheet for tracking the current year’s payments by household.
3. Excel sheet for tracking past year’s payments by household.
4. Zelle and Paypal accounts for receiving payments.

It works like this: When a neighbor makes a payment, the association gets an email notification. We manually update the spreadsheet and manually update MailChimp. We also have to manually update anytime someone leaves the neighborhood or is new to the neighborhood.

Ideas?