What's freesurfer function in aslprep?

I am processing pcasl data in aslprep and I have some doubts about the use of freesurfer. Though I include freesurfer license and the process ended with no error, in the final report it appears that freesurfer reconstruction did not run. So I wonder which is freesurfer function in aslprep? and, if I include freesurfer outputs, which data is going to be used by aslprep?
Thanks in advance!

What version of ASLPrep are you using?

We are using version 0.5.0, but we are planning to switch to 0.6.0

FreeSurfer support wasn’t added to ASLPrep until 0.6.0. Upgrading will probably fix your problem.