3
Hi,
-download the module;
-unzip (unrar ...) it to folder at your hard drive;
-check the content of that folder. Some modules are zipped with full path like http/modules/MODULE_NAME/... or only with MODULE_NAME/... folder. Be shure in there is "xoops_version.php" file in MODULE_NAME folder.
You need to upload to your XOOPS instalation "modules" folder "MODULE_NAME" with all its content. In your case MODULE_NAME will be "catads"
Sorry if my english is not very good. You may find more information in FAQ section (https://xoops.org/modules/smartfaq/category.php?categoryid=16)