What is the purpose of this inductor and cap on a RF line?
the suppler added an external component for matching. it can come for several reasons:
1. adding a possibility for frequency tuning of thee antenna, single chip will  be used for several frequencies or different bandwidths.
2. adding the matching inside the chip will increase the cost therefor the designer preferred to move out these components.
3. a mistake in  the design that was corrected using external components.

In any case, you need to use the exact instructions written in the datasheet.
Dan