You need a port. Without one, you can get by with Air Transports, except, you don't you any. I see you still have some supply stock, so you might have enough strength to take the port beside you, but I doubt it.
Even if you take the port, the germans will probably transfer Luftwaffe down to prevent supplies from flowing in.
Invasions are tricky for both sides. The germans can resupply by air, but will probably lose their entire navy to the Soviet one. The soviets can invade where they want, but wont be able to supply it. Basically if you are going to do an invasion, it is only going to be a diversion. And the units will probably die.
“My logisticians are a humorless lot … they know if my campaign fails, they are the first ones I will slay.” – Alexander the Great