Without knowing anything about the 'AccessDatabaseEngine.exe' I would say
you are running into license issues.
FME will translate a .XLS file without having Excel installed, but it will
not translate a .XLSX file without Excel installed. I believe this has to
do with .xls being more of a standard, where as Microsoft has not made
.xlsx a standard (yet?). I could be offbase on the reasoning, but I know I
have run into the issue of not having Excel installed and so not being able
to do anything with a .xlsx file, but once downgraded to .xls it works fine.
The other issue you might want to look for is spaces in your tab/page
names, I believe, and this might have been fixed, that FME does not like
spaces in a tab/page name or filename for .xls files.