首先大致分一下句子成分：
主谓：Career experts say
也就是说,that.identities 这一堆都是做宾语.
在这个宾语里面,主句是：one of the ways is to conceal their identities.
语序调整一下：To conceal their identities is one of the ways.
主语：To conceal their identities,系动词：is 表语：one of the ways
您所问的that后面引导的句子用于修饰one of the ways,所以是引导定语从句.
而从句子分析来看,that在句子中没有表达实际的意思,而主句和从句里都没有缺少的成分,所以that不做任何成分.