Certificates must be Base 64-encoded PEM-format, with a header line
including "BEGIN CERTIFICATE", as used by OpenSSL.
It looks like you have been given a certificate in a different format, PKCS#7 (p7b). You could request a new certificate from the CA in PEM format or try to convert the one you have. I do not think SGD supports that conversion, but there are tools to convert certificate formats on the web.