If you received an email that someone has purchased a charitable 'gift card' for you, don't delete it! You can use it to make a donation to any US nonprofit. You can make donations to more than one charitable organization until you've used up the gift card balance.
You'll get an email that looks like this. Click the purple "Redeem Your Gift Card" button:
A web page will open showing your gift card balance and a way to search for and select any US nonprofit, and some non-US ones:
In the lower part of the screen, select a nonprofit. We rely mostly on the official name as registered with the IRS, so abbreviations or informal names may not work.
Once you've selected a nonprofit and amount, click the purple "Donate" button.
You'll see an on-screen confirmation and also receive an email confirmation.
NOTE: the person who purchased the gift card for you received a tax receipt and, in the US, may be able to take a tax deduction for the donation. That's because the gift 'card' purchase was actually a donation to Pledgeling Foundation, a 501c3 charitable organization. Your selection of a nonprofit is just a 'regrant' of that existing gift, and you, the gift card recipient, should not take a charitable tax deduction for the amount.