Compression error: ... an error prevented a file from being processed. (527)
This error is given when a file cannot be copied because it is being used by another program. SyncBackSE/Pro can copy open/locked files, but only if certain requirements are met:
https://help.2brightsparks.com/support/solutions/articles/43000335703
If you do not meet those requirements then you must close the program that has the file open. The following article contains details on discovering which program is using the file:
https://help.2brightsparks.com/support/solutions/articles/43000335786
You may be able to avoid this error: modify the profile > Copy/Delete > tick the option 'When copying files, stop other processes from modifying them during the copy'.