Hi there! Welcome to GTPlanet!
There are many reasons why a file you find online is too big, and when you do ‘automatic conversions’ there’s also many reasons it’s too big.
I won’t go on and list everything here, but I will lead you to
this thread, where you’ll find all sorts of useful information scattered around.
I also merged your two posts, as on this forum it’s frowned upon if you double post. Worth having a read
here as well, to familiarize yourself with the dos and don’ts on this forum.
If there is anything else, don’t hesitate to ask! The GTPlanet community is a great one. I wish I could help you with your logo, but I have a ton of my own to do right now!
Good luck, and have fun!