In OT:
Render the animation as an image sequence (usually .png).
In Clip Studio:
Open the File > Batch Process window
Expand File, then expand Image.
Choose 'Current Canvas' under the Processing object section on the right side.
Press OK and select all of the images in the sequence you rendered earlier.
The images will appear as separate layers, simply create a new animation folder and drag all of the images onto it.
With the animation folder selected go to Animation > Edit track > Batch specify cells.
Choose 'Specify name of existing animation cell'.
Make sure the 'Start cell' and 'End cell' are set to the first and last frames of your animation.
Press OK.
Optionally, with the animation folder selected, choose Animation > Edit track > Rename in order of timeline, this will renumber all of the imported frames.
This should be everything that you need to do.
Check out this video for a visual guide: