Screensharing runs through a Messenger call, so the customer needs to be online in Messenger and needs to answer your call before they can share. The customer starts the share, not you.
Set up the screenshare
To see the customer's screen, start a Messenger voice call from the conversation.
Open the conversation, then click the Phone icon.
Select Messenger voice call.
Ask the customer to answer the call from the conversation in their browser.
Ask the customer to click the screenshare icon, then select the tab or the screen to share.
A recording of the call, including the screenshare, is saved on the conversation when the call ends and is available to download.
⚠️ Important: Customers cannot share their screen until they answer an outbound Messenger call from the Support team.