Hi Jonasz,
There is no library in that way in Cinema 4D to my knowledge. A decade (+/-) ago (http://charactermotion.com/support/sys_req.html) Credo was certainly usable, but todays options are different. Let me explain:
The main idea in Cinema 4D, to get a fast set up for rigging,is discussed here by Bret Bays:
http://www.cineversity.com/vidplaytut/siggraph_2015_rewind_bret_bays_creating_a_character_rigging_pipeline
To my knowledge he was in a key/lead position while developing this new system, so, this is first hand information.
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With the CMotion function, you have the option to animate repetitive movements to this rig.
With the Animation Clip system, one can set up an option to turn any compatible (rig) animation information into clips and edit the motion then like a film-editor. It needs some work, I will not say that it is a single push of a button. But it is more than powerful, to say the least.
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If you have a T-Pose or what ever would be a good fit to your model, needs to be properly scaled and then “Bind” to the mesh, in other words weighted. This can be then used to create Animation Clips.
I’m not certain how far this fits into todays animation pipeline, but I understand, you might have a larger library of Motion-captures and like to use it.
FBX is supported in Cinema 4D, but it needs a [file] version match, as in the past these files had flaws from time to time. This would be the simplest way to import your current material into C4D.
You might check out the material for the use in Unity, created by Rick Barrett. As it discusses a similar need about import/export.
I hope I got your question correctly, and my typical suggestion is, let go of the idea to use C4D as you would use 3DS, to make good progress. What is the point to change otherwise and allow the new application only to work in the way the other worked. My point is, in searching for something that works well in application “A”, you might miss the options in application “B”. Just a thought, toss it if it doesn’t work for you.
All the best
