Please find more information here.
I'm trying to help an Android user but I have an iPhone and a Mac. We can't seem to be able to connect. What are we doing wrong?
Thank you for contacting us.
Can you kindly check that setting on both devices please.
Admin side: using TeamViewer client on PC or macOS, open and use TeamViewer Remote Control on mobile device
Remote side: using TeamViewer client on PC or macOS, open and use QuickSupport on mobile device
For more information, feel free to check out this knowledge article please.