The strata plan is a legal document. If you are a lot owner, your strata manager (or strata committee) should let you have a copy of it. I cannot say who is responsible for that area outside the front door without seeing your strata plan.
By way of example, here is what my strata plan says. My strata plan is also townhouses. Each townhouse has an area called “garden court”, which is an enclosed courtyard at the rear of the lot.
“GARDEN COURTS ARE LIMITED TO A HEIGHT OF 3.66 ABOVE, EXCEPT WHERE COVERED AND A DEPTH OF 1.525 BELOW UPPER SURFACE OF GROUND FLOOR LEVEL OF RESPECTIVE ADJOINING UNIT.”
Therefore, in my strata plan, paving in the garden court would be the responsibility of the owner.
Just remember: this wording on your strata plan is going to be different. Ask your strata manager for a copy of the strata plan.