Hey there Janani!
My name is John and I'm a Guru here at Shopify!
There are definitely some donation type apps out there that you can check out to see if these would help you to put your donation scheme in place. :)
It's always worth reaching out to app developers directly to see if their app would work as you need it to and if not there might be some edits or changes you can work together on. :)
Each app store page will have a contact form and email address you can use to reach out to that app's developers for more info.
Check out the above and best of luck with everything here at Shopify!
We're currently collecting donations for equine rescues following Hurricane Harvey, so I've just done this.
We use a free app from the Shopify app store called Infinite Upsell, which will create a pop-up (actually, top-of-page section) in the customer's shopping cart, and can be used to promote any item or collection. I simply created an "item" called Donate to TEVA for Hurricane Harvey equine rescues, set the price at $5 and told Shopify not to track inventory (so they can change the quantity ordered to increase their donation in $5 increments). Then I set Inifinte Upsell to show that item at checkout. We recently had a customer donate $50 using this method, so it works beautifully... and is free!
I hope that helps. Good luck!
I'm one of the developers working on TipGenius, a simple tipping or donation pop-up app for your Shopify store checkout. We're the Staff Pick this week!
When a customer clicks the checkout button, TipGenius shows a customizable pop-up that let's you ask for a tip or a donation, and then sends the customer right through to payment. It's simple to setup and simple for customers to use.
Check us out at https://apps.shopify.com/tipgenius