The folders correspomd to different objects, as explained in the mauscript and in the supplementary document.
A programme like winrar (https://www.win-rar.com/) can be used to unzip the files. If winrar is installed, right click on one of the .zip files and select 'Extract here'.
The .zXX parts files (where XX are increasing numbers) are retrieved by the unzip programme automatically once the unzipping is started from the .zip file.
The MTF curves can be computed from the output images generated by the LabVIEW programme using the data contained in the 'slanted-edge' folder (10 sets of data are present to enable an error estimation of the resolution assessment) and the SFR MATLAB utility '04_sfr3.zip'.