Hi Victoria,
Please make sure you use the latest wpForo and wpForo Ads Manager addon versions only.
Also please make sure the wp_wpforo_ads table exists in database. Use Hosting Service cPanel > phpMyAdmin database manager tool. If this table doesn't exist, please execute this SQL:
SET SQL_MODE = "NO_AUTO_VALUE_ON_ZERO";
CREATE TABLE `wp_wpforo_ads` (
`adid` bigint(20) UNSIGNED NOT NULL,
`title` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`code` text COLLATE utf8mb4_unicode_ci,
`body` longtext COLLATE utf8mb4_unicode_ci,
`start_date` datetime DEFAULT '0000-00-00 00:00:00',
`end_date` datetime DEFAULT '0000-00-00 00:00:00',
`forumids` longtext COLLATE utf8mb4_unicode_ci,
`hide_for_groupids` longtext NOT NULL DEFAULT '',
`tpllocs` varchar(255) COLLATE utf8mb4_unicode_ci DEFAULT NULL,
`status` tinyint(1) UNSIGNED NOT NULL DEFAULT '1'
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;
ALTER TABLE `wp_wpforo_ads`
ADD PRIMARY KEY (`adid`),
ADD KEY `start_date` (`start_date`),
ADD KEY `end_date` (`end_date`),
ADD KEY `tpllocs` (`tpllocs`(191)),
ADD KEY `status` (`status`);
ALTER TABLE `wp_wpforo_ads`
MODIFY `adid` bigint(20) UNSIGNED NOT NULL AUTO_INCREMENT;
If your database table prefix is not wp_ please change it.