这类法律上的措辞（legalese）确实是读起来费劲,我的判断是针对 conditions 的.这可以从句子的组织上找出线索：
an appeal
shall be brought in such manner
and
shall be subject to such conditions as are prescribed by ...
如果是对 manner + conditions 两者,那就无需重复 shall be 了,句子可以直接写成：
an appeal shall be brought in such manner and subject to such conditions as are prescribed ...