Google Analytics Tracking ID?

Dear Madam/Sir,

I am configuring tracking by Google Analytics of shares via your plug-in.
I’m stuck at step 5 in your manual https://www.addtoany.com/ext/google_analytics/.

Google Tag Manager wants me to,

1) select a variable for Google Analytics-settings (below ‘Action Target’)
or
2) provide a Tracking-ID.

I cannot select a variable at 1), but at 2) I can.

At 2) I can choose between:

– socialAction
– socialNetwork
– socialTarget

Should I do 1) or 2), and if 2), which one should I choose from the above list?

Best,

Luca