Visa process for sponsored jobs in meta London office

Hi I recently got to know that I cleared on-site interviews for meta London via an email. I've my call scheduled with recruiter for next week. I just want to be prepared for the discussion. If anyone has completed the same process, can you please help me with the questions- What to expect in the call? I had told my recruiter beforehand that I'll require visa sponsorship. Do they have tie ups with agencies to ease the entire process? What is discussed in a team matching call? Who pays for fee associated with visa?