Migrating your SSL site to DigitalOcean or another VPS provider is easy with ServerPilot.
As long as you have access to the existing SSL key and certificate, you'll be able to use the same key and certificate on your server managed by ServerPilot.
First, migrate your app to ServerPilot.
Then, navigate to the app's SSL tab in ServerPilot.
Once there, you'll be able to paste your existing SSL key and certificate in the fields provided.