Why is the meaning of 不是要求以小组为单位做报告吗?? (...以...为...)
IMO, when 以...为... is used as a verb phrase, it should be translated to "using/taking A as B". For example, 他们以胖为美。== They take fat as beauty. 

When it is used as a prepositional phrase, we could use the prepositional word by to interpret. 

For example, 以小时为单位 could be simply translated to "by the hour". We are paid by the hour. == 我们以小时(为单位)计费。为单位 could be omitted in this case. 

Apparently, in this context, it's a prepositional phrase. So, 

不是要求以小组为单位做报告吗? 

one possible translation: 


  Isn't the demand/request to do the reporting by group?


Here 以小组为单位 could be interpreted as "by group".