Hello @Katerina1 My understanding is limited here about your requirement. To better assist you, please explain your requirement a bit - What exactly do you mean by downloading the workflow? Is it the newsletters recipients that you would like to be extracted or you would like to create another workflow similar to an existing one or would like to export the newsletter recipients workflow to another ACS instance?
1. If you want to extract the recipient's list, you can you "Extract File" activity in the workflow which has those recipients.
2. If you need to create another similar workflow, you can copy an existing one and make changes to the one copied.
3. If you need to export the workflow (one with newsletter recipients) itself, you can do that in Administrators > Deployment > Package Exports.