app for Facebook to offer signup for Constant Contact - Adobe flash based, won't work after Jan 2021

Hi - I work in a non-profit. We have a Facebook page. I thought it would be a good idea to offer FB users the chance to sign-up for our CC newsletter. When I went to do it, I got a message at FB that the app was based on Adobe Flash, which is soon to disappear. Is a replacement in the works?