My opinon is the pattern was written by a knitter that wasn’t familiar with how crochet instructions are written.
Yes, @Snowfleas, it is worked in rounds.
I would write it as follows using crocheter’s notation: (numbering the chains in parenthesis)
Sc in 2nd ch from hook (4th chain), sc in each of next 2 chains (3rd and 2nd chains), 3sc in last chain (1st chain). This is to round the end of the chain & you will now work up the other side.
Sc in each of the next 2 chains (#2 & 3), 2 sc in the 4th chain. (10 SC count).
First round complete.
This works a round of SC around the chain like a race track around the infield.
I have been thinking all day about how to describe wirkng around both sides of the starting chain.
I think they followed the knitting notation of SC1 in (named stitch), SC2, SC3 in next stitch (like a k, ktbl, k in next stitch for a double inc).
Sorry I took so long and used so many words.