You can collect recurring donations through donorbox.org. You can embed the donation forms on your Squarespace website. Donorbox.org used to be free, but now they collect a 1.75% user fee unless you subscribe to the pro plan. But it's not hard to use and you can create different buckets (campaigns) to keep track of money raised for different events, etc. If you use donorbox to collect your donations, you don't need to pay the 3% Squarespace user fee (for Business plan).