PLAN B (Points A and C)
Point A is a major city so is an attractive prospect. I would land at point C, establish the temporary port, and envelop the city.
I can set up defensive locations in the forests to the south of the city and I can bring engineers to build fortifications in the plains between the forests and along the roadway leading to city 'A'.
So the troops required for this plan to work are:
Five SMG divisions to man the forests and fortifications with machine guns and anti tank guns.
Three engineer divisions of at least 30 to 40 engineers each. One to build the port and the others to build the fortifications.
Five storm-trooper divisions consisting of SMG infantry supported by mortars to surround the city and make the final assault.
Artillery to pound the defenders of the city (the engineers will be able to quickly rebuild the city once it has been taken).
There is a chance that the troops will face quick opposition from the enemy and so the defensive divisions will need to be reinforced with a couple of other defensive divisions in reserve.
Once the city has fallen the troops will need to take the capital and smaller cities so I will need a follow-up group of armor to work in with the storm-troopers.
The locations are close enough to my home bases to enjoy air support.
PLAN C (Points B and D)
The port location, 'D', is very defensible because it is on a peninsula and is surrounded by forest.
The city, 'B', is practically worthless but the region has heavy forest and can ultimately be strongly defended.
The reason strong defenses are important is that the enemy should bleed his troops on your defenses. Usually, in a naval operation, you don't have the luxury of fighting a war of attrition.
Similar to Plan B, Plan C relies on SMG troops for both defensive and attacking roles with similar numbers of divisions as outlined above. In this plan armor is not really needed as the capital can be enveloped from the forests.
This location is close to the home bases so can enjoy air support but dive bombers are only going to have limited success due to the forests.
The X's in the forest to the south of city 'B' show the planned defensive barrier while the storm-troopers take the city.