Dear Marianna,

Tissue probability maps are included at the segmentation step. So if you choose one of the default preprocessing pipelines that contain segmentation, a GUI will pop up when you will "run" the preprocessing.
The default TPM file is already selected, which you can change.

I cannot answer regarding if you need different TPM for different subject. My guess would be yes, if you have subjects with lesions of different types.

Best,

Zaeem