Agree the crossing first
Before anyone travels, agree in the chat who crosses, which ferry they take and where you will meet. Check the ferry timetable before you agree a time, and leave room for a late boat.
Meet near the harbour
A busy spot close to the ferry terminal works well, on either side. The person crossing does not have to go far, and you meet somewhere public.
Large items
If the item does not fit in a bag, agree who brings a car and whether it crosses on the ferry.
Running late
Tell the other person in the chat as soon as you know. It keeps the arrangement in writing for both of you.