- Refresh modification cache
- Upload .ocmod.zip package of the module itself
- Refresh modification cache again
- Add full permissions for your user group in System > User > User groups
- Install extension in Extensions > Modules

Else you can also do the manual installation by ftp, if you want to do so just select all files that are in "upload" folder in module package and drop them into public_html folder where is installed your opencart (use ftp software for that like filezilla, do not do that in cpanel because cpanel is replacing folders instead of just updating files).
tion).