Open the automation for the ad you want to add the tag to.
To open the automation go to funnels > my funnels > and click edit on the automation that you want to edit.
Click add action
Click the drop-down menu and select "a tag" and then click select
If your desired tag is already created you can select it in the drop-down menu. If you need to create the tag you can click "create new tag" and type in the desired tag. For example, "Buyer," as shown below.
Click "Add Event" - use the hourglass ⏳ on the left side to adjust the time frame. Not necessarily needed for tags unless you want the contact to be tagged a specific tag at a specific time of the automations. You must hover over the automation to reveal the ⏳.
Repeat this process for any other automations.