On Anna’s archive I see volumes 1-7 as cbr files. You probably did this already, but there are multiple mirrors to the same files to choose if one doesn’t work right. All the libgen.li files 1-12 are on there as cbr, too.
The best way to make a complete volume is to do this manually:
change .cbr to .rar or .cbz to .zip by renaming the entire file extension. (xyz.cbr to xyz.rar) Then extract them to be in the folder name they were extracted from.
Cbr is just a rar file for comic books and cbz is a zip file. My android tablet can extract rar and zip folders natively.
For Windows, you may have to use WinRAR or something else if you are using a computer. You will have to have show file extensions on to do this step.
Keep the picture files in the extracted folders. If the names of the issue folders are not in order by number, rename them and them place them in a single folder.
You can do this to make it easier:
1_foldername 2_foldername
Name the main folder to whatever you like as it will be what you see after everything is done. Like: comicname_complete
*I am unsure if it will work, but to see a thumbnail for the complete volume you could put a single picture file in the main folder.
Zip the main folder back up to .zip or .rar and then rename the extension back to .cbz or .cbr.