FormGuard, FormNotifier, FormRanger
Open the Google Form editor, refresh the tab, then use the Add-ons puzzle-piece menu or the add-on entry shown in the Forms editor.
Start by refreshing the file, checking the account that installed the add-on, and opening it from the correct Google app. FormSuite add-ons are split between Google Forms and Google Sheets, so the right first click depends on the product you installed.
After installing from Google Workspace Marketplace, reload the current file. Then open the add-on from the host app it was built for. A Forms add-on will not appear inside a Sheet, and a Sheets add-on will not appear inside a Form.
Open the Google Form editor, refresh the tab, then use the Add-ons puzzle-piece menu or the add-on entry shown in the Forms editor.
Open the target spreadsheet, refresh the tab, then check the right sidebar and Extensions > Add-ons for the installed add-on.
Use the same Google account that installed the Marketplace app. If a Workspace admin installed or blocked apps, the menu state may differ by account.
Use this path for FormGuard, FormNotifier, and FormRanger. Create or open a test form, refresh the tab, then open the add-on menu from the Forms editor.
Use this path for FormCopy, FormMerge, and DocForge. Open the target spreadsheet, refresh, then open the add-on from the sidebar or Extensions menu.
Create a blank test Form or Sheet and look for the add-on there. This separates account/install issues from one file's state.
Disable extensions that block sidebars or popups, and try a normal Chrome profile where you are signed in to the correct account.
Include the add-on name, host app, account type, where you looked, and whether Marketplace shows the app as installed. Do not include private form responses or sheet data.
Do not start with a real batch. Run one small first proof, confirm the visible result, then leave a short Marketplace review only if the first test worked.
These Google help pages explain how Workspace add-ons are installed, where they appear, and how to manage installed Marketplace apps.