Hi,
I presume you are trying to add and run it on a Windows PC, and you have Net8 on it.
My approach:
1. Likely you have already done it, but download the latest version zip and unzip in a new folder C:\CumulusMX-NewVersionDownloads and it should then have a folder C:\CumulusMX-NewVersionDownloads\CumulusMXdist4070 with all the files and folders in it. Any futures updates would also go in this folder and would have the file name with the new version.
2. Make another new folder C:\CumulusMX which will be your running folder.
3. Copy in all the files and folders from the C:\CumulusMX-NewVersionDownloads\CumulusMXdist4070 to this other C:\CumulusMX folders so all the unzipped files and folders are now also in C:\CumulusMX
4. You can now start CumulusMX in File Explorer by going to the C:\CumulusMX folder and right-click on the file CumulusMX.exe and select Run as Administrator.
If you have an existing CU1 or CMX with data then you can copy-in the previous version's Cumulus.ini (configuration file), the \data and \Reports and you're all set.
Possibly some more details needed in your install, but that is the basics.
Enjoy,
Paul