Having issues with long file paths also when trying to set permissions? Check out this guide on how to find long paths and correct them.
First you’re most likely going to need to take ownership of the data before you will be able to set the perms, my preferred method is to use takeown.
takeown /F ROOT_FOLDER /A /R /D /Y
/F filename Specifies the filename or directory name pattern. Wildcard "*" can be used to specify the pattern. Allows sharename\filename. /A Gives ownership to the administrators group instead of the current user. /R Recurse: instructs tool to operate on files in specified directory and all subdirectories. /D prompt Default answer used when the current user does not have the "list folder" permission on a directory. This occurs while operating recursively (/R) on sub-directories. Valid values "Y" to take ownership or "N" to skip.
Once you have taken control you can then set the perms with the below.
icacls ROOT_FOLDER /grant DOMAIN\USER:F /t