Can't join to any minecraft server and skin doesn't show in singleplayer.

Whenever I try to connect to a Minecraft server, it says: "the authentication servers are currently down for maintenance", and also my skin doesn't show in any singleplayer world.

Probably has something to do that when I redeemed my prepaid code I signed up with a Microsoft account instead of a Mojang account.

What I expected to happen was...:
That I would play peacefully in an SMP with my friends.

What actually happened was...:
I got the error message that I already explained, and when I got into a singleplayer world, it didn't load my skin.

Steps to Reproduce:
This always happens, and it's been several days (I really don't know exactly the cause of this)