See if your serial numbers (with download instructions) are on your Magix Account (section My products).

If not, try your old SCS account on https://www.sonycreativesoftware.com/. Click My account there and log in with the email address and password you used there and go to My software. If you find the S/N, go to https://www.magix.com/us/support/my-service-center/product-downloads