Apparently you have to wait until 4th of september to dock in order to start the coastal waters mission.
I too really want to love this game. I install it once a year, play a little bit. Get frustrated and uninstall because of the numerous bugs. TWOS do fix some of the vanilla ones, but brings in its own share of new ones.
On the bright side, there is a new submarine simulation game under development called Uboat, that looks promising.
https://store.steampowered.com/app/494840/UBOAT/