i want to copy files in a ADLS gen2 account to another ADLS gen2 account in different subscriptions

i want to copy files in a ADLS gen2 account to another ADLS gen2 account in different subscriptions and then later I want to sync the files in it.

the number of files to copy is 20 million files and 72TB in size. 

Please help us determine, which is the best tool to realize this in azure cloud.