No, they really can't. They literally lack the weapons and most major powers on Earth have enough firepower to take down Space Marines. They're fairly large, wide targets and their armor can't stop anti-armor weaponry. That means this boils down to logistics, which is simply not in the Imperium's favor. They don't have the troops, they don't have the armor, and they don't have the industrial base to outcompete the planet. Trying to do so is simply a recipe for disaster.
No, we don't.
At least not if you actually go with the canonical abilities of Space Marines and their armor.
Guided weapons? Won't work, the ECM in their armor would fry anything we have.
Man portable weapons? Space Marines could aim dodge anything a baseline human could do.
Tanks or other armor? A single bolter round would kill an Abrams.
Aircraft? Again, a single bolter round is more than capable of taking out essentially any aircraft that gets within line of sight. And Astartes can make the shot the first time, every time.
Insurgency? Every Space Marine is able to eat a humans brain and basically instantly learn everything they know. Language, codes, friends, strategies, tactics, relationships, networks, etc.
The global telecommunications system is in the hands of the Tech Marines within literally minutes of their arrival in orbit. Every satellite is either co-opted or removed as the first act and thus denies Earth GPS, surveillance capabilities, satellite communications, etc.
Nuclear weapons? Battle Barge sensors are able to detect and track nuclear warheads from orbit. Thus the weapons are localized and then either captured or removed as part of the opening moves, long before any good targets for them are within their range.
Earth also lacks anything to slow, deter, block, counter, or otherwise interfere with orbital strikes. This isn't 40k where the enemies have at least somewhat comparable technology and are operating on the same level.
Detecting power plants is fairly trivial, and with a relative handful of strikes you can knock out the power grid globally.
The Astartes call upon Earth to surrender and Earth either does so or it is conquered in a long weekend. Any large scale military formation is an easy target for orbital strikes. Any insurgency efforts get brain ripped.
Someone will be willing to play ball, a Librarian will make sure they are being honest, and the Astartes will support them as a local administration is established.
Short of Chaos deciding to interfere, nothing Earth could do would credibly slow, much less prevent, an Astartes conquest with the level of resources that the OP provides.
